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

The search for a missing man reveals a murder plot stranger than fiction

Screenplay for Murder 42:09

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.'"