It's one of the most stunning views in Southern California. It's also the site of one of the most shocking crimes.

A tiny 4-year-old girl out on a special daddy-daughter date takes a terrifying tumble. Her father says she accidentally slipped over the edge. But when investigators get out to the scene, their stomachs drop. It's no seaside playground. It's a perilous cliff with a terrifying drop 120 feet down. Was the little girl's fall a freak accident, or is it possible this father did the unthinkable?

One detective fights every day to find the answer. He will not rest until he discovers what really happened to this beautiful little girl up on that cliff.

Lauren Key loved singing, playing with dolls and dancing. She was a typical 4-year-old girly girl.

"I'd always liked the name 'Lauren,' so when she was born I looked into her baby-blue eyes and just knew the name was perfect for her. It just fit," said Sarah Key-Marer, Lauren's mother. "She was very happy, open, friendly and kind."

But Lauren's mother says there was something that tortured her smiling daughter every day. Lauren was the highly coveted centerpiece in a nasty tug of war between her mother and father, Cameron Brown, a rugged outdoorsman who liked to ski, surf and run marathons.

Cameron Brown was often seen tooling around ritzy Newport Beach, California in a souped-up Army truck.

"We met in Newport Beach at a jazz bar," said Sarah.

Brown was an airport baggage handler. His job was hurling 50-pound pieces of luggage on and off airplanes. And before long he'd also swept the British rose off her feet, whisking Sarah away on vacations. But just a few months later, their whirlwind romance comes to a crashing stop when Sarah finds out she's pregnant.

"He chose not to be part of the pregnancy," said Sarah.

Did he want you to keep the baby?

"He'd expressed that he did not," said Sarah.

Brown finally appears to embrace his impending fatherhood. But then something inside him snaps.

"He started pressuring her to have an abortion. When she refused to do that, he threatened to have her deported," said L.A. County Deputy District Attorney Craig Hum.

Craig Hum says Brown even tried to have Sarah fired from her job when she refused to end the pregnancy.

"When that didn't work, he just cut off all contact with her and had absolutely no contact with her at all," said Hum.

By the time little Lauren is born, Cameron Brown is completely out of the picture.

"For the first few years of her life he wasn't part of her life, but that was his choice," said Sarah Key-Marer. She says he never asked to meet his little girl.

"Sarah wanted there to be some kind of a relationship, so there was nothing preventing him from having a relationship with Lauren," said Hum.

Sarah raises Lauren on her own, but eventually the financial toll overwhelms the single mom.

"Sarah was just having difficulty making ends meet, and so what she did was she filed a petition for child support, and he was ordered to pay child support," said Hum.

One of Brown's airport co-workers says the absentee dad constantly complained about the hefty payments.

"He was paying a thousand dollars a month in child support, which was about 40 to 50 percent of his income," said Hum.

And that's when Brown reportedly comes up with a devious plan.

"He told one of his friends, 'I heard that in order to get your child support reduced, you have to request visitation, and so that's what I'm going to do," said Hum. "His initial request was for 33-percent custody and joint legal custody, and he'd never even met Lauren."

Sarah says she was nervous, but Lauren, now 3 years old, couldn't wait to finally spend time with her dad.

"I think initially Lauren was excited to meet her father," said Sarah.

"The first few visits went OK, they were supervised by Sarah, but pretty quickly friction started to develop and there were issues," said Craig Hum.

Sarah tells me the happy-go-lucky little girl suddenly becomes troubled and withdrawn.

"I would detect anxiety and tantrums that increased as the visits went along," said Sarah. "She became very fearful and scared of things that she hadn't been before.

"She had said that she did not want to go. She would hide under the bed, but the court order said that she had to go, and it broke my heart to have to let her go," said Sarah.

A few weeks before Thanksgiving in 2000, Cameron Brown arranges an afternoon visit with Lauren. Sarah says she's still haunted by what happened early that morning.

"I had dropped her off at her preschool, and as I hugged her goodbye, I told her that her father was collecting her, she immediately started to cry and hold onto me. It was hard to separate. The teacher had to come out and pry her from me. I assured her everything would be fine, she was gonna have a great afternoon. The last words I said to her was 'I love you,' and the last words she said back to me also were the same," said Sarah.

Throughout the morning Sarah can't stop thinking about Lauren.

"She called the school a couple of times to see how Lauren was doing, and the teachers told her that she was still upset but she was doing OK," said Craig Hum.

In fact, the teacher tells her Lauren was too upset to eat her favorite lunch, a peanut butter and jelly sandwich.

"Sarah was so distraught about the impact that this visit was having on Lauren that she made the decision that even with the court order ordering visitation, she was just not going to let it happen that day," said Hum.

So Sarah heads out to pick up Lauren at school, but it's too late. Brown's already there.

"The teachers reported that she didn't want to go with her father. She was crying, he had to physically pick her up and carry her out of the preschool," said Hum.

Brown drives Lauren to Palos Verdes, a seaside town just south of Los Angeles, where he lived. He's planned a hiking trip with the 4-year-old up to a remote cliff in a secluded area called Inspiration Point.

"No parent, nobody would take a 4-year-old child out there," said Craig Hum.

They make the nearly 1-mile trek to the cliff and end up sitting on a rocky ledge overlooking the ocean. While Lauren tosses rocks into the raging Pacific Ocean below, Brown says he looked away for a split-second, and when he turned back, his little girl was gone.

"He just saw her feet as she went over the cliff head first," said Hum.

"The cliff wasn't just a straight drop into the ocean. There was a slope and there were projections of rock out from the top of the cliff," said L.A. County Deputy District Attorney Craig Hum.

Cameron Brown says Lauren ran the entire way to the rocky ledge, a terrifying 120-feet drop straight down to the ocean.

"He said he didn't see her when he looked over the edge of the cliff," said Hum. "He ran down to a beach that was on the other side of the cliff and he borrowed a cellphone to call 911."

Cameron Brown: "My daughter fell off a cliff in Palos Verdes."

911: "OK sir, are you near her or can you see her from where you are?"

Cameron Brown: "No, I haven't gone down and found her. I just found someone with a phone and called you first. Now I'm going to go look."

"Rather than going to her body or to try and rescue her, he spent about four and a half minutes talking to the 911 operator," said Hum.

911: "Does he know where he is?"

Cameron Brown: "It's a sunbathing beach

911: "A sunbathing beach?"

Cameron Brown: "Yeah, you know, where the nude bathers go. [Aside] You guys might want to get dressed, ha. Sorry."

"As one witness described it, it was like he was ordering a pizza. There was no emotion," said Hum. "And all the while his daughter is floating face down in the ocean, and he is chatting on a cellphone and joking with the people at the beach."

Brown eventually makes his way down the shoreline in search of little Lauren. It's been nearly 15 minutes since she slipped and fell. Then he spots her lifeless body floating face down in the water.

"Her little beautiful body was broken and battered," said L.A. County Sheriff's Homicide Detective Danny Smith. "It wasn't anything that any parent should ever have to see or, or any parent would ever in their worst nightmare ever see."

Detective Smith and his partner Detective Jeffrey Leslie don't usually respond to accidents. But something about Brown's 911 call and the location of Lauren's fall was troubling.

"There's no way that a kid should be out on that cliff. I've been out on that cliff," said Det. Smnth.

On a hunch the detectives head to Inspiration Point to speak to Cameron Brown.

"I went to introduce myself to Mr. Brown and I remember coming back to Danny and saying 'I don't like this, I don't like it,'" said L.A. County Sheriff's Homicide Detective Jeffrey Leslie. "He was so disconnected, it just didn't feel right."

"I looked over at him, I said 'That's the dad?'" said Det. Smith. "And someone said 'Yeah, that's him,' and I was struck by the absolute poker face, lack of emotion, and very nonchalant."

"He was more concerned about his surfboard on top of his car," said Det. Leslie.

An hour away from Inspiration Point, Sara Key-Marer and her new husband are worried. Their little Lauren is late coming home.

"We decided to drive up to where her father lived, and we were on the phone with the police trying to find out if there was any accidents, and we were directed to go to the nearest police station," Sarah tells Crime Watch Daily. "So when we got there we were met by a detective. It was all quite a blur to me.

"They mentioned the word 'cliff,' and there'd been a death and it involved Lauren, but I couldn't piece everything together. I remember becoming hysterical.

"I was just cascaded into this emotional pain. I just remember wailing, heaving, no words were coming out," said Sarah. "I feel my reaction was what any parent, how they would react if they'd just heard the worst news of their life."

Cameron Brown's behavior is getting more bizarre by the minute.

"He showed no interest in what had happened. Instead he wanted to know who had won the presidential election," said Craig Hum.

Maybe Brown was just in shock. But there was something the detectives, who were both fathers to kids Lauren's age, couldn't explain away: Why would a dad take his 4-year-old to such a dangerous place?

"Interestingly, Jeff and I are both afraid of heights," said Det. Danny Smith. "He would only go so far and I'd only go a little bit further, and we were still at least 30 feet from where Cameron said that he took his daughter and sat on the edge of this cliff.

"We finally called our SUV, special enforcement bureau, and said, you know, we need some people up here rigged up with rappelling gear," said Smith. "We wouldn't walk out there."

Did you believe Cameron Brown's version of what happen on that cliff?

"It was very difficult to comprehend what he was saying is what happened. It was just such a bizarre death," said Sarah.

When the detectives finally get a glimpse at little Lauren's body, it's like a punch in the stomach.

"She didn't have the injuries to support a slip and a fall," said Det. Leslie.

"She would have scrape marks on her hands on her arms, on her face, and she showed none of those injuries," said Craig Hum.

So what happened to little Lauren Key on that cliff?

"She had to be propelled," said Det. Jeff Leslie.

"Based on the nature of her injuries and based on the force with which she would have had to have been thrown," said L.A. County Deputy District Attorney Craig Hum.

"That she died at the hands of her own father was incomprehensible," said Sarah Key-Marer.

No one, especially Lauren Key's mom Sarah, wanted to believe a dad would or could throw his own child to her death. But the evidence seemed to be overwhelming.

What was the forensic evidence?

"They examined the edge of the cliff, the examined the dirt, the brush, the weeds, and there was just no scuff marks, there was no evidence of slipping or sliding or any disturbance along the edge," said Craig Hum.

The county coroner agreed, releasing a disturbing 32-page report ruling Lauren's death a homicide.

What were the injuries on her body that indicated that this was not an accident?

"If Lauren had accidentally fallen and slipped, she would show significant sliding injuries, significant abrasions, because the cliff wasn't just a straight drop into the ocean," said Craig Hum. "She showed none of those injuries. Just one sudden impact, which was consistent with her being thrown clear of the edge of the cliff and landing on a single projection about 100 feet down, before bouncing off the cliff and then going into the water."

But detectives Jeff Leslie and Danny Smith want to prove their theory beyond a reasonable doubt. So they bring in a team of experts in biomechanics to reenact the incident. They fill a box with 40 pounds of weights, about what 4-year-old Lauren weighed at the time of her death, and they go back to Inspiration Point. Then they hurl the box about 10 feet, the distance they estimate Cameron Brown could toss his 40-pound daughter. Brown was an airport baggage handler who tossed 50-pound suitcases for a living.

The results were chilling.

"The defendant actually placed one hand near the top of Lauren's back and literally threw her off of the cliff, so that she cleared the edge of the cliff, rotated from a head-up to head-down position, and struck the rock face first with her back away from the cliff and her face into the cliff," said Craig Hum.

Why would a dad kill his own flesh and blood?

"The defendant and Lauren's mother, Sarah Key-Marer, didn't get along at all," said Hum. "Their child custody battle was very contentious."

And cops say that's one of the saddest parts of this story: Brown killed his own daughter just so he wouldn't have to pay a few hundred bucks a week in child support. As detectives are putting the final pieces of the puzzle together, they keep a close eye on Cameron Brown.

"I think Jeff and I both were like 'This is kind of that mentality, the guy, like a Unabomber,'" said L.A. County Homicide Det. Danny Smith.

Brown had lived off the grid in a remote cabin in Colorado. Detectives knew if Brown ran, they might never find him. So they put a surveillance team on him, and lo and behold, their detectives' intuition was right.

"It was either the day before Thanksgiving or Thanksgiving Day, and our surveillance team called me and said 'I think this guy's gonna get on and take off,' and I said 'Arrest him,' and that was that. He went to jail."

Based on the box test and the autopsy on little Lauren Key, Cameron Brown is charged with first-degree murder and lying in wait. Everybody thought the case would be a slam-dunk.

"There's not anyone, in my opinion, who is reasonable that would take his story and say 'Yeah, I could see that happening,'" said Det. Smith.

But jurors are skeptical.

"Jurors just don't want to believe that that a man would murder his daughter, period, and certainly not by throwing her off a cliff into the ocean," said Craig Hum.

Cameron Brown may be the most hated father in the country, accused of throwing his 4-year-old little girl Lauren Key off the side of a cliff just so he wouldn't have to pay a few hundred bucks a week in child support.

"The innocence of the victim makes the crime that much more hideous," said Det. Danny Smith.

And possibly the most sickening part is that after Brown murdered his daughter, detectives say, he went back and ate his daughter's leftover peanut butter and jelly sandwich out of her lunchbox.

"I mean, to me, it puts you in the category of sociopath," said Det. Smith.

Brown maintains the only thing he's guilty of is not being able to save Lauren when she accidentally fell. But who would the jury side with? The verdict comes in, and the prosecution is floored. The jury is deadlocked.

"There were a couple of reasons," said L.A. County Deputy D.A. Craig Hum. "The jurors had trouble convicting the defendant of murder when there were no eyewitnesses to say 'I saw him throw her over the cliff.' But I think the bigger problem with the case was just the unwillingness of some jurors to believe that a man would do this to his daughter, and in such a horrible way."

"I just couldn't make sense of it," said Lauren's mother Sarah Key-Marer. "It was a huge disappointment at the time."

"I think I just said we weren't done. 'We're not done, and we'll keep fighting until we are done,'" said Det. Leslie.

Jeff Leslie wasn't about to give up. He and partner Danny Smith were determined to get justice for little Lauren.

"We kept working on Lauren's case and we never gave up on it," said Det. Smith.

And prosecutors say the dogged detectives' tireless work on the case lands a new lead.

"After the first trial he located additional witnesses who proved to be significant witnesses as well," said Craig Hum.

Nearly three years later, the district attorney decides to try Cameron Brown's case again. It's a completely different jury, but the outcome was shockingly the same.

Detective Danny Smith decides to hang up his badge, and he retires. But desperate to find justice for little Lauren, Det. Leslie goes back to the D.A. and asks what will it take to get a guilty verdict.

"He knew that if there was anything else out there, if there was any other information he could get, that he was gonna get out there and dig again," said Hum.

And there, in one of the dozens of binders Det. Leslie had filled with notes, he spots a name. It's a baggage handler who worked with Brown who was never interviewed.

"He was able to locate a witness who recalled back shortly before Lauren was murdered, how the defendant would complain about the child support payments," said Hum.

"Their comment was something to the effect of, 'Wouldn't it be nice if we could just kill them and get rid of them,'" said Det. Leslie.

With that witness, they headed back to trial for a third time. But would that one witness be enough to tip the jury?

"Obviously I hoped for justice and wanted us to win," said Det. Leslie.

"Everybody was on edge," said Craig Hum.

This time it takes the jury just over 36 hours to reach a verdict: guilty of the crime of murder in the first degree.

"Guilty on all counts," said Det. Leslie.

Even jury members rejoiced.

"I think that I heard Sarah sobbing in the audience," said Craig Hum. "I looked at the detective who was sitting next to me, and there was just an overwhelming sense of relief that justice had finally been done."

"I think it finally set in," said Det. Leslie. "I remember when I turned over my shoulder and looked directly at Sarah, we just kind of made eye contact like, 'We did it, and we're done.'"

It was a long, emotional 15-year fight for justice for Lauren.

And just when he thought he could rest, Det. Jeff Leslie found himself in another battle: This one for his life, against an aggressive form of blood cancer.

"I'm doing OK. I have good days and bad days, been through a lot of treatment, a lot of chemotherapy, had a bone marrow transplant and my son was my donor," said Det. Leslie. "I think I was on my death bed a couple of times."

"He's probably the toughest guy, mentally and physically, I've ever known in my life," said Det. Danny Smith. "I mean there's no quit in him. Lauren's case shows you that. There's no quit, he's not going to give in to this thing."

"I would like to thank Detective Leslie from the bottom of my heart for his loyalty, his hard work and dedication, because without this, there would be no justice for Lauren," said Sarah Key-Marer.