Two young women, total strangers connected in the most horrible of ways by a true psychopath with evil intentions.

The case started in Denver, led investigators all over the state of Colorado, and ended with an arrest that may have saved countless lives.

Denver Police had no idea a psycho-sexual maniac was in their midst until a beautiful 19-year-old college student named Kenia Monge mysteriously went missing, on April 1, 2011.

Kenia's stepfather Tony Lee thought his wife Maria was messing with him when she called him on the morning of April Fool's Day, saying the teenager was nowhere to be found.

"And I said 'OK Maria, this is not the proper April Fool's joke.' And she says 'No Tony,'" Tony Lee tells Crime Watch Daily.

Tony was as frantic as Maria. He loved Kenia like his own flesh and blood, helping raise her since she was 12 after he married her mom.

"In the beginning, very shy. As we went along in the relationship, she was, there was something different about her," said Tony.

Something that magically endeared her to Tony.

"She says 'Can we just say 'Daughter, father?' And I said 'If that's what you want, yes,'" said Tony.

Kenia was also a model big sister to Tony and Maria's two younger children, Kimberly and Anthony.

"She liked being a boss. She liked telling Kimberly and Anthony what to do. Loved it," said Tony.

And they loved growing up with her looking out for them.

"It just blew my mind, 'cause she was just so happy, always brought so much joy to the house, made everybody happy," said Anthony Lee.

"She was like a bright light for everyone," said Kimberly Lee. "She was beautiful. Everybody, all the guys, I remember at school, I used to be like 'Oh my goodness, like, what's going on? Why do all these guys keep talking to me about my sister?'"

Kenia had such a kind heart that she even taught a Sunday school class she'd started up herself for the younger kids at her local church.

"She had leadership qualities, but she was no different than any preteen or teenage girl either," said Tony. "I still had to get on her about homework, cleaning, boys, phones, all the normal stuff."

But Kenia had grown into a beautiful young lady who'd just enrolled in college after graduating high school with dreams of carving out a career for herself in broadcasting. She found herself a job as a customer service representative to pay for her education and her rent.

"She had moved out. She was living with her boyfriend and getting on with her life," said Tony Lee.

That is, until Kenia Monge suddenly went missing while on a night out with some friends.

Did you even know Kenia was out that night?

"No, I did not know," said Tony.

Tony was shocked to learn from Kenia's friends that they were all out drinking and partying at a nightclub, even though they were under age.

"I had no idea about this party life that she had," said Tony.

They hade secretly been going bar-hopping for years.

"She and all of her friends had all obtained false I.D.s. They were going to the 21-and-over clubs in downtown Denver," said Tony.

If that was all Kenia had done that night, Tony says he could have been understanding.

"I did the same thing. I think every teenager does it," said Tony.

But Tony is horrified when Kenia's friends tell him another secret, that a wild Kenia had to be escorted off the premises by security staff.

"They said it was because of intense intoxication. She was so drunk that they had to kick her out," Tony tells Crime Watch Daily.

Into the empty streets of Denver in the early hours of the morning wearing a black miniskirt and red high heels.

"Without her purse, without her phone, without her jacket," said Tony.

Who had all that stuff?

"Her friends did. It was left in the bar," said Tony.

It's so out of character for Kenia that Tony immediately suspects someone at the club may have spiked her drink.

"She was just so out of control," said Tony. "Her friends said they were drinking together and no one had more than anyone else did, and they didn't feel out of control or anything like that."

Maybe someone did slip a drug in her drink?

"That is what we believe," said Tony.

And there's one other disturbing detail that sends chills down Tony's spine.

"She was kicked out with a guy that she was doing some inappropriate things with on the dance floor," said Tony. "And it was not her boyfriend."

An alarmed Tony Lee takes the information he's uncovered to police. And rather than wait for them to begin investigating, an impatient Tony turns detective himself, scouring Kenia's cellphone in search of any clue to the identity of that mystery man who'd been thrown out of the club with her.

"I see all these names and all of these messages, and I'm going through there," said Tony.

One of the messages screams out to him.

"And it said 'Hey, this is Travis, guy from last night, white creepy van. Did you get home OK?'" said Tony.

Nineteen-year-old Kenia Monge had just gone missing after being kicked out of a nightclub where she'd been drinking and partying into the early hours of the morning. Everyone is still hoping she'll turn up, suffering from nothing worse than a bad hangover.

"They thought maybe she's somewhere with somebody, and she's sleeping it off, or whatever," said Tony Lee.

But Kenia's stepfather Tony fears otherwise after retrieving the phone she'd left at the club and discovering a bizarre text message from a strange man the next day. Tony thinks it may be from the mystery man who'd been thrown out of the club with Kenia.

"That's why I did want to talk to him. That's why I continued to call him," Tony tells Crime Watch Daily.

He left a message and anxiously waited for Travis to call back.

"That is the only communication with that Travis up to that point," said Tony.

But police following up on a missing-person report Tony had filed made a dramatic discovery. Surveillance video shows Kenia and the mystery man shortly after they'd been kicked out of the nightclub together in the lobby of his apartment building.

"We interviewed him," said Denver Police Det. Nash Gurule.

He tells police that Kenia had walked home with him.

"He tries to talk her to go into his loft," said Det. Gurule.

And she agrees, only to suddenly change her mind after getting there.

"He says that he wanted her to stay. She said 'No, I have to get back to my friends.' Then she leaves," said Det. Gurule. "Within five minutes, she's outside the building."

She's seen talking to a homeless man loitering near the lobby before briefly going to a neighboring hotel to use the bathroom.

Based on the videotape, does she look highly intoxicated?

"She looks intoxicated, yes. Staggering, kind of trying to hold up her balance, stuff like that," said Det. Gurule.

Do you believe she was just drinking, or could maybe someone have slipped something into one of her drinks?

"You know, anything's possible," said Det. Gurule.

Kenia returns to the front of the apartment building -- then vanishes.

"You could see her walk out of camera view," said Det. Gurule.

Denver Police might never have learned what happened to Kenia Monge after that if not for her stepdad Tony Lee, who finally got a call back from Travis.

So now we are 48 hours after Kenia was last seen?

"Correct," said Tony.

Travis tells Tony he'd seen Kenia stumbling on the street outside the apartment building.

"He got out and asked her 'Hey, you need any help? Is there anything I can help you with?'" said Tony.

Travis says he gave her a ride back to the club in that "creepy white van." And when they find it's closed, he offers to drive her all the way home.

How does he say the night ended?

"As they were leaving downtown, she wanted a cigarette," said Tony.

So Travis says he stopped at a gas station along the way, only to find that's closed too. But he says Kenia got out of his van to bum a cigarette from another man smoking nearby.

"Sat down, smoked, talked with him. They got up and they left together," said Tony.

Travis says he left too.

And then, did you say to him, "So how exactly did you get Kenia's phone number?"

"I did ask him that, and he said 'I let her use my phone to call her phone to talk to her friends,'" said Tony.

Travis then offers to meet Tony at the gas station where he says he left Kenia.

"And I said 'When can you be there?' He said, 'I'm on my way.' I said 'I am on my way also,'" said Tony.

Were you a little concerned about your own safety?

"I was concerned to the point where I went upstairs to my bedroom and I got my 9mm pistol," said Tony.

But Tony is in for a very different surprise when he arrives at the gas station.

"When I pulled into the front, I saw two police cars there," said Tony. "It's like, 'How did this happen? How did these policemen get here?'" said Tony.

It was only later that Tony learned his wife Maria, fearing for his safety, had called police after he left the house.

And Travis -- full name Travis Forbes -- goes to the police station for questioning.

Travis Forbes is the last known person to see Kenia Monge alive, and as police start looking into his story, it seems to hold up.

Forbes tells detectives just what he'd told Tony Lee, again insisting that Kenia had walked off into the night with the guy she was smoking with, and that was the last he'd seen of her.

Forbes provides detectives with an alibi, along with a witness who can verify it.

"He says 'I went to my girlfriend's house afterwards,'" said Det. Gurule. "At the same time we have other detectives that pick her up, bring her in, and she corroborates the story. And she says 'Yep, he was with me from abut 3 o'clock, 3:30, till like 7 or 8 in the morning when I woke up.'"

Forbes tells detectives he wished he'd driven Kenia all the way home.

"If she had made the choice to go back home, or to get in my van, I would have taken her home," Travis Forbes tells detectives in a recorded interrogation.

But Forbes says he had no idea she was in any danger.

"I mean, if I felt any sort, any sort of weirdness about her walking off with that guy, I wouldn't have, I would have done something," Forbes tells detectives.

Forbes describes the man with Kenia at the gas station as a young Asian named "Dan," who becomes the main person of interest as police launch a massive operation to find Kenia Monge, or at least learn what happened to her.

"We had detectives from a homicide unit, the missing-exploited persons unit, fugitive unit," said Det. Gurule. "We had so many detectives working on this case, running down video, running down leads, picking people up for interviews."

Kenia Monge had gone missing without a trace, and now so has Travis Forbes.

"So we start looking for him," said Denver Police Det. Nash Gurule.

Travis Forbes's sudden disappearance puts him back on police radar. That led them to search a downtown Denver bakery, where Forbes made his own line of granola bars.

There they uncovered chilling surveillance video of him wheeling a cooler into the freezer the night Kenia vanished.

Anything in it?

"Bleach," said Det. Gurule. "It's been bleached. It was washed. We found one human cell on the drain plug."

And when police search Forbes's van, it oddly appears to have been scrubbed spotlessly clean.

"It smells like bleach in this van. There's new carpet on the floor. Something ain't adding up," said Gurule.

But Travis Forbes was nowhere to be found. Until police got word he'd just been arrested in Austin, Texas for driving a car that had been reported stolen by an acquaintance in Denver. Det. Gurule goes to Austin with a warrant to get a sample of Travis Forbes's DNA.

"And when I walk in, he is pretty shocked that I'm there," said Det. Gurule.

Travis Forbes was extradited back to Denver. But the acquaintance whose car he'd taken declines to press charges -- so he can't be held any longer.

"We put undercover officers on him," said Det. Gurule. "They watch him for two days, and we're hoping that he'll take us back to Kenia, and he doesn't."

Just two days after police end their surveillance of Forbes, something happens that suddenly and tragically changes the entire course of the case. As police try to figure out what happened to Kenia Monge, about an hour north of Denver, a horrible crime provided some pieces of the missing puzzle: another young woman is ferociously attacked in Fort Collins, Colorado, in July.

"He attempts to kill Lydia Tillman," said Det. Gurule.

Forbes broke into Tillman's apartment, raped her, strangled her and mercilessly beat her senseless, before dousing her with bleach and leaving her to burn to death.

"Her apartment is set on fire," said Det. Gurule.

But a brave Lydia Tillman miraculously escapes with her life.

"She jumps out a second-story window," said Det. Gurule.

Lydia Tillman is left so badly injured that she initially can't even tell medics who attacked her.

"Because she can't talk, because her face is smashed, her jaw is shattered," said Det. Gurule.

At the hospital, while Tillman fights for her life in a medically induced coma, investigators find DNA under Tillman's fingernails and rush it to the crime lab. It comes back, and detectives have a match: It's Travis Forbes. And when Tillman finally comes out of her coma, she identifies Forbes as the man who tried to kill her.

"And they charged him with attempted murder, sex assaults, I mean a slew of charges," said Det. Gurule. "And now we know where he's at, so now I could focus solely on my evidence."

That includes Forbes's cellphone records that show his girlfriend, Kerry Humphrey, was lying when she gave him an alibi on the night of Kenia Monge's disappearance, saying he was with her.

"The phone doesn't even show close to her house at the times that she says that he was with her. Doesn't even show him ever at her house," said Det. Gurule.

At some point you just confront Humphrey and say "We know you're lying"?

"Yes we do," said Det. Gurule

She gets arrested for lying?

"Oh yes," said Gurule.

Now Travis Forbes's story that he had nothing to do with Kenia Monge's disappearance has completely fallen apart. And confronted with the overwhelming case against him, Forbes dramatically confesses to raping and strangling Kenia to death in a plea deal to save himself from the death penalty.

"I killed her. I did not mean to kill her," Forbes tells detectives in a recorded interrogation.

Forbes claims he didn't even plan to kill Kenia the night he gave her a ride in his van.

"I didn't pull over to kill her. I didn't pull over to rape her. None of that was in my head. None of it was premeditated," Forbes tells detectives.

Forbes tells Det. Gurule that Kenia had fallen asleep in his van.

"He says he has sex with her while she's asleep. He says that she wakes up and she's upset. She slaps him for having sex with her when she is asleep. And he chokes her. Kills her," said Det. Gurule.

Forbes puts her body in a cooler that he had in his van to deliver his homemade granola bars to customers.

"He talks about how he tries to shut the lid of the cooler and it won't shut because her arm's springing up because rigor set in," said Det. Gurule. So he closes the cooler and tapes it shut. So for hours he drives around with Kenia in the cooler in the back of his van."

Then Forbes takes her back to his bakery, where everything he does next is captured on security video.

"He gets a little cart, puts her on the cart, takes the cooler into the freezer," said Det. Gurule.

Before he later dumps the evidence in a barrel.

"Takes her out of the cooler, strips her, washes her with bleach, strips himself, washes himself with bleach, takes everything out of the van, washes it down, sprays it down with bleach and burns it in that barrel," said Det. Gurule.

Forbes led detectives to a remote rural area outside of Denver where he'd buried Kenia's body.

"He gets out of the truck and he says 'She's down there by the trees,'" said Det. Gurule. "It's kind of like a ravine and then a grove of trees. And I walked down the ravine, and he's like screaming and crying and he says 'You're standing right on top of her.' And he tells the other detective she's about five feet down."

And you found Kenia?

"Yes," said Gurule.

Not the way everyone wished.

"No. Not the way I wished," said Gurule.

Not the way her devastated family had wished either. Kenia's stepdad Tony has to break the news to Kenia's mother and siblings.

"They lost it, and there was nothing I could do for them," said Tony Lee.

Kenia's sister Kimberly, now a mother herself, still can't believe it.

"I really truly believed in my heart that my sister was still alive and that she was still going to come back home to me," Kimberly Lee tells Crime Watch Daily.

Kenia's brother hasn't recovered from the heartbreak either.

"That pain is still there. It's just never going to go away, no matter what," Anthony Lee said.

The family would never be the same again. The tragedy ended Tony's marriage to Kenia's mom Maria.

"There's no second of no day that this is not there. It's just this thing, it's just there. It's always there," said Tony Lee.

But amazingly, family members of Travis Forbes's victims would somehow find it in their hearts to forgive him. Young heroine Lydia Tillman recovered and expressed those sentiments herself at Forbes's conviction for attempted murder.

And Kenia's sister has even corresponded with Travis Forbes in prison, where he's spending the rest of his life for Kenia Monge's murder.

"To sum it up, he pretty much says, like, 'Kenia didn't deserve what happened to her that night, she seemed like she was a great person,'" Kimberly said.

Is he able to explain what it is within him that makes is possible for him to kill people?

"He said he's evil. He said he is a dark person and he just doesn't know why he did it," said Kimberly.

In fact Travis Forbes said in his confession to Kenia's murder that he may be dangerously insane.

"Something I need to do is find out what the definition of 'sociopath' is, because I'm pretty sure I fit it," Travis Forbes is recorded saying during an interrogation.

Forbes also hinted that he may have killed other women.

"I want to confess. I want to confess so bad."

"Because there are more victims out there we don't know about? It's just a matter of time before they come up. Why are you nodding your head yes, but you won't say anything?"

What do you make of this man? Is he a serial killer?

"He could be, yes," said Det. Nash Gurule.

Forbes himself says the world would be horrified to know his secrets.

"When everything comes to light, it's going to be horrific. Horrendous," Forbes says.

And Kenia's dad says he certainly wouldn't be surprised to learn that she wasn't the only young woman Forbes had murdered.

Do you believe that Travis Forbes is a serial killer?

"I believe Travis Forbes is a serial killer, yes," said Tony Lee.

Lydia Tillman has made an amazing recovery from her injuries and now teaches yoga in Colorado.

As for the family of Kenia Monge, her father has now started a foundation in her name. Its mission is to help families of people recently gone missing.

"There's a lot of things I can help a family with during those first few days, because there's no book on this," said Tony. "There's no 'how-to' guide. I just got all this stuff in my head about what you need to be doing on the legal level, what you need to be doing on the personal level, what you need to be doing with your family, and how to do a proper search."

For more on how you can help support the foundation, visit The Kenia Monge Foundation.