Was "Dexter" fanatic's diary a screenplay or murder confession?

Produced by Lourdes Aguiar and Anthony Venditti
[This story was originally broadcast on Feb. 11, 2012. It was updated on July 10.]

(CBS) EDMONTON, Alberta -- Lured to a garage on the pretense of a date with an attractive woman named "Sheena" he thought he met online, 33-year-old Gilles Tetreault was now being held hostage by an apparent madman in a scene straight out of a horror film.

"When I first saw him... I look back, and -- and I see this man-- kinda hovering over me with a hockey mask. ...There's this chill down my back, as I - 'Wow, this is no date,'" Tetreault told "48 Hours Mystery" correspondent Troy Roberts. "He's about 6 foot and has a black and gold hockey mask painted -- all painted up on his face."

The hockey mask wearing man had ordered him to the ground at gunpoint.

"And he tore a piece of tape and he covered my eyes with it," he continued. "And I start hearing different things....like a jingling noise and stuff like that...my head is just racing, like it's like thinking, 'What's goin' on? What's he gonna do? Is he takin' another weapon out?'"

Tetreault decided he wasn't waiting to find out.

"I can't do this, I gotta fight back ...so I got up and I ripped the tape off my eyes...And he was stunned that I got up and started yelling at me to get back down on the ground."

Instead, he grabbed the attacker's gun.

"And when I pushed it away and grabbed the gun, I felt the gun was plastic. This is the greatest feeling I ever felt in my life, because then I knew I had a fighting chance to get away," Tetreault said. "That's when I was ready to fight ... I punched him and I felt really weak. I'm like, 'Wow, why was my punch so weak?'"

What Tetreault didn't realize was that he had been weakened by the effects of the stun baton. "And then he starts punching me on the side of the head."

Just about then, he came up with a plan.

"He grabbed my jacket, pulled my jacket and I jerked around again to make sure he had a hold of it and I thought, 'it's time. It's the perfect time,'" he said.

"That was part of your plan, you're thinking, 'he grabs my jacket and I can get free...'" commented Roberts.

"Right. And that's when I slipped out of the jacket, rolled underneath the garage door and then got up...And it worked!"

But the developing real-life horror movie plot was far from over.

"And I tried to run and all of a sudden my legs didn't work...I just fell, boom right on the gravel driveway. ...That's when he grabbed my legs and started pulling me back to the garage. ...So, I'm like, 'oh no, what am I gonna do now. I'm dead.'"

Tetreault was thrown back into the garage, but he surprised himself and the assailant by rolling out again. Terrified, he ran into the alley collapsing in front of Marisa Girhiny and Trevor Hossinger, a couple out for a stroll.

"We were stunned," said Girhiny.

"Yeah, we were just totally stunned," said Hossinger.

Asked what Tetreault said to them, Hossinger replied. "He said he was getting robbed and 'Can you help me?'"

"They didn't know what to do," Tetreault explained. "And all of a sudden the -- the masked man came back out. And I -- and then I pointed to him and I said, 'That's the guy!'"

"And then the mask guy, he went around the corner here and just watched us," said Girhiny.

"And so I believe he started pretendin' he was my best friend," Tetreault said. "He said something like, 'Come on, Frank, or come on friend.' ...And he -- kind of gestured to me like we were playing."

Girhiny says she started to panic.

"You thought this was a trap," said Roberts.

"Yeah, we thought we were gonna get robbed," she replied.

Fearing for their safety, the couple walked quickly away, leaving Gilles Tetreault to fend for himself as he retrieved his truck.

"So I started walkin' back to the -- the garage," he said. "And then sure enough I see his feet in the garage and he's pacing back and forth in the garage ... And so I quietly got my keys out of my pocket. I stuck the key in the ignition...and then I just sped away."

When Tetreault went home, he discovered the profile had been deleted and he did his best to erase his own memory.

"Why didn't you go to the police immediately?" Roberts asked Tetreault.

"At first I was in shock. I told myself I'll do it tomorrow. And tomorrow came and I was...I felt so ashamed that I got duped," he said.

Embarrassed and confused, Tetreault convinced himself that perhaps it wasn't as serious as he first thought.

"I really thought it was a mugging at the time," he said.

But Tetreault didn't know how wrong he was. Just one week later, Johnny Altinger, another lonely bachelor, would answer a similar dating ad... and disappear.

Photos: A closer look at the evidence

Gary Altinger, Johnny's older brother, says the last time anyone heard from him was on Oct. 10, 2008, when the 38-year-old computer enthusiast left for a date with a woman named "Jen."

"Where is he? What's going on? He wouldn't do this to us," Gary Altinger said. "Not a message, nothing. ...And then, not showing up for -- for work? Totally...out of character. ...John was very, very, very responsible."

What happened next made no sense at all.

"And when did you grow concerned?" Roberts asked Altinger.

"When I received that email...And this e-mail was completely out of character," he replied.

"What did it say?"

"'I've met a woman named Jen. And I'm going away with her to -- Costa Rica and I'll call you at Christmastime.' I just thought right away after I read this, that's gotta be the weirdest message I've ever received," replied Atlinger.

That identical strange message had gone out to all of Johnny's friends as well.

"What did John's friends do?" Roberts asked.

"They contact the police and say, 'OK. I think it would appropriate to send out a missing persons. There's something wrong. Something doesn't feel right. Something isn't right,'" Altinger replied.

But police paid little attention. Desperate for some answers, Johnny's friends broke into his apartment.

"They found his passport. And they found dirty dishes. And they found everything just like as if he were going to return an hour or two later," Altinger said. "And with that information, then they went to the police and they said, 'Hey, listen. You've got to do something.'"

This time, the police were listening. Veteran homicide detective Bill Clark was part of the investigation.

"So we talked about and decided, obviously, our first priority was to try and find John. ...His red Mazda was missing," Det. Clark said. "He had taken his vehicle, it couldn't be found. So obviously that's what we're gonna look for first. Easier to find a car than a person."

"Based on the emails, they talk about Costa Rica, the officers search all the parking lots at the airport," Clark continued. "It's not found, you know? ...Everything's turning up negative."

But there was one clue that would give police their first big break in the case. On the day he disappeared, Johnny Altinger had forwarded the directions of where he was going to friends.

"Well, John's friends were concerned," Clark said. "And his friend even questioned him on the email. You know, this -- 'you know, be careful...'And John said, 'Yeah, well, here's the directions. And if anything happens to me, you'll know where to look.'"

Armed with the directions, police are led directly to a garage.

"They learned, of course, the garage is rented out to an individual named Mark Twitchell," said Clark.

Mark Twitchell, a 29-year-old married father and aspiring filmmaker, had used the garage as a set for a recent movie project.

Twitchell denied knowing anything about a missing man or a red Mazda and he has no problem with the police wanting to search the garage. But he points out something odd about the lock.

"He had gone to the garage and made some comments about a lock being changed," Clark said. "And, you know, based on what I've been told, I'm going, 'OK, this sounds like someone else has been to this garage and tampered with it...'"

Cops pried the lock off and in they all went.

"And -- they have a look around and they see...what looks like blood," Clark said. "And Mark Twitchell's explaining, 'Oh, no, that's my movie prop. We did a film about killin' a guy in here and I filmed it all. And I've been cleaning it up over the last couple weeks...'

"And there are some things that were, you know, raisin' your Spidey senses in this one," Clark continued. "Goin', 'Yeah, this isn't right...Something goin' on here.'"

For detectives, the disappearance of Johnny Altinger was a mystery in more ways than one.

"It's a missing persons case," Detective Bill Clark said. "We don't know if foul play's happened here. We -- we don't have a body. We don't even know if we have a crime."

Their only lead was Mark Twitchell's film set garage. Voluntarily, the amateur filmmaker came down to the Edmonton Police station to speak with detectives:

Detective: Altinger. Does that name ring a bell to you or mean anything to you?

Mark Twitchell: No.

Detective: Never heard it before?

Mark Twitchell: No.

Twitchell was eager to help. He came from a good home, had no history of violence, and was hardly a suspect. In fact, he seemed guilty of nothing more than wanting to brag about his film career.

Mark Twitchell: I'm working on a comedy right now. Which is a -- it's actually a full-blown feature that's actually gonna have a decent budget in the neighborhood of about three-and-a-half million...

Mark Twitchell's first film project, a "Star Wars" fan film, had received some media buzz in 2007.

Jimmy Siokos, an actor and screenwriter who played Han Solo in the film, was struck by Twitchell's enthusiasm.

"He was a big kid at heart, like a lotta 'Star Wars" fans are," Siokos said. "He set up everything...We were just excited to get the ball rolling and start -- start filming.

...On the surface everything looked great."

But it soon became clear though that Twitchell may have had grand plans, but he didn't think them through.

"He was not prepared at all," Siokos explained. "He had gotten his money. ...He had permission to use this big studio. ...That was the extent of it. ...His fan film...fell apart."

Video: Hear more from Siokos on what it was like to work with Mark Twitchell

Photos: A closer look at the evidence

Yet reality didn't seem to dampen Twitchell's ambition in the least.

"Here's this guy saying, 'Directing is in my blood' and 'I'm gonna do this the rest of my life' and 'I'm gonna make great movies,'" Siokos continued. "He was as delusional as any person I've ever met in my life. ...He wanted to be somebody at any cost."

As the police interview continued, detectives questioned Twitchell about his last production, a suspense thriller called "House of Cards." The plot? A hockey-masked serial killer lures a man to a garage via the internet and kills him.

Detective: I mean it's kinda odd that you're filming that kind of thing.

Twitchell: Mm hmm.

Detective: And we end up going to that garage because of a missing person who supposedly went there.

Twitchell: Yeah. It's really freaky too...And as soon as they called me on the phone...I got this weird chill.

"He looked pretty comfortable in the interview," Det. Clark said. "And when it was done and I watched, I went, 'Wow, that guy interviewed well.'"

Hours later, Mark Twitchell even agreed to let officers back into the garage where he had filmed "House Of Cards." Little did they know the case was about to take an unusual turn.

"Detective Murphy goes, you know, and meets him and talks to him," Clark said. "And there's this huge revelation about, 'Oh yeah, I bought a red car off a guy.' It's like -- I remember getting the phone call at the police station just thinking, 'Holy crap.'"

That's because police were still looking for Johnny Altinger's red Mazda. So investigators called Twitchell again. And again, he voluntarily agreed to answer more questions. This time, Bill Clark conducted the interview.

Detective Clark: So as you know Mark we're just here trying to find this John fellow. John Altinger

Mark Twitchell: Mmm hmm.

Clark listens while Twitchell tells him how he came into possession of a red car -- a detail he failed to mention when he spoke with police earlier.

Mark Twitchell: This guy, uh, taps on my window...You know, "Hey buddy do you wanna buy a car? ...I -- I've shacked up with this really rich lady...She's even gonna buy me a new car...so I'm just looking to unload mine...how much do you have on you?"

Mark Twitchell claimed he bought the red Mazda for just $40 and that it was parked at a friend's house.

"What are you thinking when you hear that? That he purchased a car for $40?" Troy Roberts asked Clark.

"I just thought, 'That's unbelievable.' Right away I'm saying to myself this is a bunch of crap," he replied.

The serial killer movie being filmed and the strange story about the red car ... for Clark, could only mean one thing.

Detective Clark: There's absolutely no doubt in my mind that you're involved in the disappearance of John Altinger. No doubt in my mind at all Mark.

Mark Twitchell: Why?

But it was only a hunch. Detective Clark had no hard evidence against Twitchell and was forced to let him go -- though he wasn't going to make it easy.

"Then when we walked outside...and I said, 'Oh, by the way, I'm taking your car.' ...And he says, he kind of fumbled for a bit, and said, 'Well, I need to get somethin' out of it.' And I said, 'Well, you're getting' nothin' out of it.' ...We were really worried that he was gonna be destroying some evidence," Clark said. "I said, 'I'm gonna get a search warrant and search that car.'"

While waiting for the warrant, police began digging deeper into Twitchell's background. They were interested in speaking with anyone who had worked on "House Of Cards."

Enter Chris Heward, whose character meets an untimely, bloody end in the film.

"My character was killed with a Samurai sword. ...They said they would have a mannequin or a dummy to run the sword through, and when I got there, there was none," Heward explained. "When I looked at the weapons...that was my first sign. ...When I saw that they were real, I thought, 'This is off ...Why didn't I tell somebody where I am?'"

Heward left the garage film set unharmed but rattled. His unease only escalated when police asked him about that allegedly fake movie blood they had spotted in the garage.

"'How much of the blood splatter on the wall was from your filming?' I said, "None of the blood splatter was from us,'" he said.

Video: Hear more from Heward about his bizarre filming experience

The detectives' concern for Johnny Altinger's safety intensified when they made an unexpected discovery in Mark Twitchell's maroon Pontiac, which bore the plates "DRK JEDI."

"In that vehicle we found-- a laptop computer," Clark said. "They pulled off the hard drive a deleted file...titled "SK Confessions."

"SK Confessions". Police believed "SK" was shorthand for "serial killer."

Detective Clark said, "One of the first lines...it says -- 'I'm not sure when I decided to become a serial killer, but it was a feeling of pure euphoria.'"

"SK Confessions" told the story of a man who was lured to a garage and stabbed to death. It was a plot strikingly similar to "House Of Cards". "I plunged the knife deep into his neck..."

"It was unbelievable, Clark said. "I just remember reading it all and just was fascinated by this document going, 'Holy mackerel.'"

But was the document a screenplay? Or was it in fact Mark Twitchell's confession of murder?

Two weeks after the disappearance of Johnny Altinger at a garage film set, police had sharpened their focus on filmmaker Mark Twitchell.

"It just didn't make sense and you know what...if it doesn't make sensewhere there's smoke there's fire," said Det. Bill Clark.

Police cameras were rolling as a forensics team processed Twitchell's car and the garage he rented.

Seven miles away, detectives had been at the Twitchell home, where they found Jess Twitchell, Mark's unsuspecting wife of two years.

"What I said was, 'We're investigating a missing person, I believe your husband's got somethin' to do with it...and this quite possibly -- you know, could be a homicide,'" Clark said. "I didn't really go into anything more, but I think that was enough. I mean, she was emotional."

Police soon discovered that the Twitchell marriage was already fractured.

"They had been livin' and basically sleeping in separate bedrooms," Clark explained. "She was basically livin' on the main floor, he was livin' in the basement. So, there was obviously troubles in paradise there, we knew that..."

Twitchell had been having an affair with an old girlfriend and lying to his wife about having a job.

"We found out he was telling his wife he was going to work every day. He had no job," Clark said. "He was getting his friends to invest in his alleged movie making business with his Hollywood connections... And basically Mark Twitchell was living off their money."

Curiously, the document police had found in Twitchell's laptop titled "SK Confessions" also referenced a crumbling marriage and secrets.

It read: "I went through great lengths to bring my wife over to the comfortable belief I wasn't cheating on her."

"It was basically almost like a movie script," said Clark.

Photos: A closer look at the evidence

But what was real and what was fiction? The closer police looked, the more the lines blurred. Police discovered Twitchell spent countless hours making elaborate Halloween costumes.

"It's almost like, at times, Mark Twitchell lives in a fantasy world," said Clark.

But it was Twitchell's Facebook page, comparing himself to TV's fictional serial killer Dexter Morgan, that really raised eyebrows.

"Mark has way too much in common with Dexter Morgan" read Twitchell's Facebook status.

"He talked a lot about how he loved the show 'Dexter,'" said Clark.

Twitchell even posed as Dexter Morgan on Facebook.

"We all have a dark side...some darker than others and you're not the only one to relate to Dexter....I mean it sometimes scares me how much I relate...I mean look at this profile," Renee Waring said, reading Twitchell's Facebook message.

That profile had caught the attention of Waring from Cleveland, Ohio.

"I'm a huge fan of the Showtime show, 'Dexter' -- as well as the books. So I thought, 'Oh, well, you know, I'll be friends with him,'" she said.

Eventually Twitchell revealed his true identity.

"He was a filmmaker.... and he was working on a new thing called 'House of Cards,'" said Waring.

Waring was intrigued. After all, she was an aspiring writer and a friendship with a movie maker could open doors.

"I thought it was gonna be like a working relationship, a working friendship. You know, we had a lot in common," she said.

"So, I mean, you spoke to him a couple of times a day online? Was it flirtatious?" Roberts asked.

"Oh yeah. Absolutely," she replied. "And I'm just a flirt, you know, with anybody."

Their email exchanges soon became dark; it was shortly before Johnny Altinger disappeared.

"We talked about, you know, serial killers...and, you know, the psychology behind a serial killer," said Waring.

At the time, Waring was upset with her ex-husband's new wife.

"And I wanted her dead, at the time...But I said I couldn't do it," she told Roberts. "And hypothetically, how would you get away with it?"

"How do you get away with it?" he asked.

"He said, 'You cut her up in little pieces. You put her in trash bags, like 'Dexter.' And since I was close to the lake, 'you rent a boat and -- dump her out in the middle of Lake Erie,'" she said of their conversation.

For Waring, all the dark talk was just a twisted fantasy... that is, until she received a disturbing email from Twitchell in mid-October.

"He said over the weekend he did something and he liked it," she said. "'I crossed the line and I did something and I liked it.'"

"And what did you take that to mean?" Roberts asked.

"That he killed somebody. What other line is there to cross?" she replied. "Something inside my head just gave me red flags and said, 'He did it.'"

Renee Waring tried to get Mark Twitchell to confess to her, but he never did; however, one of his last emails confirmed her fears.

The email read:

"There's an enormous missing person, possible homicide investigation going on centralized around a location I've rented for film work...So of course the police have tossed my house and impounded my car...Not fun considering they won't find anything..."

But Twitchell had underestimated the police.

"He thought he was way smarter than the police," Det. Clark said. "One of the biggest mistakes I think that he made was he had no idea how we do our job and that was a huge advantage to us.

Adding to their circumstantial case: Twitchell possessing Johnny Altinger's car, the "SK Confessions" document, and his "Dexter" obsession. Investigators finally had hard evidence: they had found Johnny Altinger's blood in Twitchell's trunk.

"When we got the word that the DNA matched, we briefed our tactical team -- our arrest team, and we had officers ready to make the arrest," said Clark.

On Halloween morning 2008, while Mark Twitchell was putting the finishing touches on his Halloween costume at his parents' home, police were busy laying a trap.

"You know, we got an undercover operator to work the internet and pretend he was gonna -- an investor," Clark explained. "He was lured out on the promise to meet this guy at this coffee shop...And when he got about three blocks from his house, the tactical team swooped in on him and took him down. Tough guy Mark Twitchell peed his pants he was so scared. And it was a little taste of his own medicine, I guess."

Back at the station, Det. Clark and Twitchell came face to face in the interrogation room once again.

Detective Clark to Twitchell: As I told you that night, last time, I knew that you were involved in the disappearance of Johnny Altinger. That's changed slightly...I now know that you killed John Altinger.

Three weeks after Johnny Altinger's disappearance, police charged Twitchell with first-degree murder. The once talkative movie director barely uttered a line.

"You didn't get much of a reaction did you?" Roberts asked Clark as they watched the interrogation video.

"No, he's uh -- well he knows not to say anything...he's talking to his lawyers. He's not gonna admit to anything," he replied.

Mark Twitchell didn't have to. "SK Confessions", which police had been dissecting word by word, spoke volumes. They were now convinced it was no screenplay, but rather a diary of murder.

One passage about a knife read: "I thrust it into his gut. His reaction was pure Hollywood."

"We do believe, as investigators, that the account written by Mark Twitchell in the 'SK Confessions' is exactly what he did to John Altinger," said Clark.

But there was a crucial part of the story they couldn't verify... about a victim who had survived.

"It was just a huge piece of evidence 'cause not only would it verify what was written in 'SK Confessions'...it would also have -- a living witness... so it was paramount that we find this person.," he said.

Detective Bill Clark's years in the hockey rink have taught him a valuable lesson: keeping your eye on the goal is often the key to victory.

And now the game plan was finding the alleged victim who had escaped from Mark Twitchell's garage.

"You know, one of the first things we did was check the police records...figuring hopefully someone called the police on this. And we have nothing," said Clark.

But police had found a helpful clue during the search of Twitchell's home.

"One of the things they had found was a hockey mask...the 'SK Confessions' talked about how...Mark Twitchell had worn this mask when he attacked both victims. But we figured it was something the first victim would key on," the detective explained.

Police soon took to the airwaves:

"We have some details on this male victim who was attacked, and would like him to come forward," Detective Mark Anstey told reporters while holding up a photo of the hockey mask.

Photos: A closer look at the evidence

Gilles Tetreault was at home, oblivious to the horror he had escaped, when a friend told him to watch the news.

"To date, we do not know who this victim is," Det. Anstey continued. "I believe this victim entered the garage and was attacked by another male who was wearing a hockey mask..."

"And it's the same hockey mask that I saw," Tetreault said. "Wow, yeah, this is -- this is the guy. This is what happened to me. It's the same mask, everything."

What Tetreault heard next came as an even greater shock: Another man had been lured to the same garage and met a gruesome end.

"...We have not found John Altinger's body," said Anstey.

"And what were you thinking when you heard this?" Roberts asked Tetreault.

"I couldn't believe it. ...Once you -- find out the whole story...I knew at that point it was not just a mugging. It was actually-- he was probably going to kill me," he replied. "And I'm like, 'Wow, I -- I have to go forward now. I have to come forward.'"

Exactly one month after he was attacked, Gilles Tetreault walked into the Edmonton Police Department and told police his incredible story.

"I was off balance, I couldn't ...I couldn't run... "I fell down on the gravel driveway and, uh, basically crawling," Tetreault told police.

"It was just an unbelievable interview. It...had me on the edge of my seat," Clark said. "I'm sitting there going...it's like watching a movie on TV going, 'What's gonna happen next,' you know?"

But in reality, Detective Clark knew exactly what had happened next.

Tetreault told police, "So he drags me back to the garage."

His story matched nearly word for word what was in "SK Confessions": "I grabbed him by the leg as if to drag him back into the garage caveman style."

Read excerpts of Twitchell's diary

"So, I know that this diary that we have is true," said Clark.

"After this all happened, I realized how lucky I was," Tetreault told police.

Seven days after Tetreault was attacked, police say Twitchell wasn't going to make the same mistake twice.

"How did he kill John?" Troy Roberts asked Clark.

"We know that he lured him to the garage in the same way that he lured Gilles Tetreault," he replied. "And then in this case...because he learned from Gilles that the Taser didn't work, he hit him over the head with a lead pipe."

From "SK Confessions": "Please stop hitting me ...oh my skull."

Following the narrative, police believe John Altinger was then stabbed and dismembered on a makeshift autopsy table.

"What was the most damning piece of evidence you discovered?" Roberts asked.

"We had a, you know, luminol test done on the floor," Clark explained. "Large amounts of blood had been spilled on the floor of the garage. Probably one of the biggest pieces, a piece of tooth that was found inside there. That piece of tooth matched up to our victim."

According to "SK Confessions", the killer then broke into Altinger's apartment and sent out those emails about taking an exotic vacation.

The killer then attempted to burn the remains in a barrel, but failed. He next tried to dump them into the river, but was afraid of being seen.

"Ultimately, Mark Twitchell drove around with it, according to the 'SK Confessions' document," Clark explained. "He even talked about driving around with him and pulling up beside people at red lights and looking at them thinking that 'they don't know I have a dead body in the trunk of my car.'"

But where was Johnny Altinger's body? "SK Confessions" described the killer finally choosing a sewer to dump the remains, but that's where the pages stopped; it was a story without an ending.

"In any homicide investigation, you obviously want to bring closure to the family," Clark said. "So not only do you want to make that phone call saying, 'We got the guy that did this to your loved one,' but in this case, we wanted to say to 'em, 'Look, we found Johnny.'"

Detective Clark hoped Twitchell would provide the final chapter.

"You guys were driving around and there was a camera trained on him in the back of the police car. Tell me about that," said Roberts.

"When you...read all the expert's books about these type of individuals, is they tend to like the media attention," Clark said. "So we thought, 'Well, maybe if we drive him around and we'll put a camera on him, maybe he'll just-- we'll just take him to places,' 'cause we had no idea where Johnny's remains were at that time."

"So in order to finish the movie, we have to find the body, take it back to the people, the family -- done. The movie's over and you can write it all down," Clark said to Twitchell in the car.

Detective Clark was relentless, taking Twitchell on a tour of his old neighborhood.

"And we first drove to his parents' house where he had been staying," Clark explained. "We actually...demanded that he tell us. He wouldn't."

"Look familiar Mark? Are we parked right on top of the sewer where you dumped the body?" Clark asked Twitchell in the car,

Next stop: The scene of the crime.

"So here we are back at the killing garage, the 'Dexter' garage," Clark said to Twitchell while standing outside the garage. "Bring back any memories? Want to tell us where the body is now? Get this over with?"

Video: Ride along with Det. Clark and Mark Twitchell

Twitchell remained silent, so police kept searching on their own... looking in sewer after sewer.

"So all these manhole covers were pulled off in this alley," Clark explained. "So anytime I'd seen one I'd always have my flashlight with me and would get out and actually take a look."

Weeks, then months, passed and still no luck. Frustrated, police would pay Twitchell many visits at the jail where he awaited trial, trying to get it out of him. Then, on June 3, 2010, a year-and-a-half after Johnny Altinger disappeared, the homicide unit received a call.

"Mark was willing to turn over something to the police," Clark said. "And right away, when I heard about it, I'm going, 'he's gonna turn over Johnny.'"

But did the filmmaker have one last plot twist?

Nearly two years after his arrest, Mark Twitchell was finally ready to break his silence about the whereabouts of Johnny Altinger's body.

"He had three conditions though. One was the police couldn't ask him any questions, the second one was no media could be present - and no Bill Clark," Det. Clark said with a laugh. "So I kind of chuckled at that, so I thought, I got to him."

So detectives met Twitchell in jail, where he gave them a Google map to the location where they would find the remains.

Police followed the map to an alleyway, ironically located just a half block away from where they had stopped their search.

"And he had marked an 'X', 'X' marks the spot, and took us right to this sewer cover here," Clark showed Roberts. "We could see what looked like pieces of human torso down there."

For Johnny Altinger's brother, Gary, the news was devastating.

"When something like that happens to somebody you love...you don't wanna believe it... because the truth is really, really difficult," he said.

In March 2011, Gary Altinger faced his brother's accused killer in court.

Edmonton Crown prosecutors Avril Inglis and Lawrence Van Dyke had a lot to work with.

"Considering Mr. Altinger's blood wasn't just all over the garage...it was on Mr. Twitchell's clothes when he was arrested three weeks later. That's a lot of evidence," said Inglis.

"We felt it was just, like I say, without a doubt, the strongest case I've ever gone to court with," Clark said. "But you always go in with a jury trial going, 'You never know.'"

Adding to the evidence was the infamous "SK Confessions" document. Prosecutors called multiple witnesses to prove that it was Twitchell's diary... and who better to prove their case than Gilles Tetreault, who came face to face with his attacker at the trial.

Photos: A closer look at the evidence

"I wasn't really afraid of him at that time," Tetreault said. "I knew he couldn't hurt me anymore."

"How important was Gilles testimony?" Roberts asked Inglis.

"One of the most important aspects...was his ability to confirm the truth to the document that Mr. Twitchell had crafted," she replied.

The courtroom was mesmerized as "SK Confessions" was read out loud.

"When we actually were in front of the jury presenting...that very graphic, gruesome horrific evidence -- it was a full courtroom and you could -- you could hear a pin drop," said Van Dyke.

"At times, Mr. Altinger's family was present in the courtroom. And...you could hear them," Inglis said. "You could hear their -- their reaction. You could hear them crying."

Jurors heard a weeping Jess Twitchell, the filmmaker's now ex-wife, testify that Mark had confided in her that he was incapable of feeling empathy for others.

"That was...the first time Mr. Twitchell had seen her since the time he was arrested -- over two years earlier," said Van Dyke.

Throughout it all, Mark Twitchell sat emotionless until Det. Bill Clark took the stand and the interrogation tapes were played.

"He watched his wife testify, he watched his girlfriend testify, with just a blank stare on his face. No emotion," said Clark.

"Yet, he's watchin' the video of me, and he starts to puff up and starts to cry," Clark continued. "And he turns around to me...and he says to me, 'I'm sorry for lying to you.' And then I put my hand up and said, 'Whoa, Mark, you can't talk to me right now.' And I just thought, 'Oh, it was so phony.'"

"What did you say to Mark Twitchell in court?" Troy Roberts asked Gary Altinger.

"I called him a f------ piece of s---," he replied.

"And what did he say?"

"He didn't say anything. He would never look at me," Altinger said. "No matter how often I looked at him, no matter how often I stared at him (shaking his head), no. He would never look."

In the end, the only witness the defense called was Mark Twitchell, and the storyteller had one incredible tale, starting with "SK Confessions, "which he said was largely fiction and shorthand for a famous horror writer.

"If you believe Mark Twitchell in court, it was Stephen King, but everybody knows it means 'Serial Killer Confessions," said Clark.

Twitchell claimed that Altinger's death was nothing more than a "House of Cards" publicity stunt gone horribly awry. He called this PR scheme "MAPLE", an acronym for "Multi-angle Psychosis Layering Entertainment."

"He talks about how he was creating an urban legend, and how he had -- was gonna lure Gilles in and Johnny in, and there was never any intent to kill them. And they were gonna just be part of this urban legend," Clark explained. "It would be about a guy who lured people to a garage, and they got away and that was the whole plan."

Twitchell argued he had let Tetreault go so that he would create a buzz when the film came out by telling people that this had actually happened to him in real life. But he claimed Altinger became enraged at being tricked, and that he accidentally killed Johnny in self-defense.

"He actually expected everyone to believe him in court," Clark said. "I...had a tough time not getting out of my chair and just going, 'That's a bunch of crap,' you know?"

And the jury agreed. They took just five hours to find Mark Twitchell guilty. He was sentenced to 25 years to life.

"To me he's a psychopathic killer that we've taken off the streets of this city. There's no doubt in my mind or I think in any of the investigative team that he would've kept on killing. We caught him on his first one," Clark told reporters.

The only question that remains is why? Detective Bill Clark is convinced that in Twitchell's mind, he thought he could make the ultimate serial killer film -- if he became one.

"I think that ultimately, his goal was to produce a movie on what he had done," Clark said. "He could sit back while he's producing it and just go, 'These guys are all acting this out, but in real life I've actually done it.'"

For Johnny' family, the pain will never go away.

"I miss his intelligence, his wit -- his helpfulness," Gary Altinger said of his brother. "If I ever had a problem...you could always count on him. ...And he would come and visit. ...You know, he'd spend some time with my kids."

"You said that your children suffer from nightmares," Roberts commented.

"They have," Altinger replied. "They remember their uncle fondly. And they miss, they miss -- they miss him."

Gilles Tetreault struggles with feelings of guilt, but meeting Johnny Altinger's mother has helped in his recovery.

"I didn't know how she'd take to me 'cause I survived and her son didn't. You know, how -- how she'd be with me," he said. "She was so nice. ...She grabbed my hand, and she thanked -- she said, 'I'm so happy you're still with us.' And that was so nice," he continued, holding back tears.

"Still emotional for you?" Robert asks Tetreault.

"Yeah. Yeah. Yeah it is."

For Tetreault, life has changed for the better. He now has a son. But the reality of just how close he came to death that day and how lucky he was is not lost on him.

"If I woulda died that day, my son wouldn't have even been born. ...I think about that all the time," he said. "I don't know if it's -- the willpower to live...or some higher power was looking over me that day, but -- I thank God that I -- I got away."

Crown prosecutors have decided not to charge Mark Twitchell with the attempted murder of Gilles Tetreault.

In February 2012, Twitchell dropped his appeal.