It was far from the perfect crime -- but a seemingly random murder just outside Baltimore would stump detectives for years.

In Dundalk, Maryland, a young couple's lives were shattered when a boyfriend arrives home to find his girlfriend dead -- her throat slashed.

Heidi Bernadzikowski's childhood friend Karen Zukley says after Heidi graduated from high school, she was ready to spread her wings. Heidi got her own place and picked up a new hobby, playing pool. And while out playing one night, she scores big: she meets a new man named Stephen Cooke.

Their attraction is instant, and the relationship moves fast. Within a few months, Heidi and Stephen, who works in the plumbing department at Lowe's, move in together in Dundalk, Maryland.

In late April 2000, around 5 p.m., Stephen Cooke picks up Heidi Bernadzikowski from work downtown in the car they share. He takes her home, then runs some errands. When he returns a few hours later, he opens the door and crosses the threshold to a nightmare: Heidi's throat has been cut.

When Baltimore County Police arrive, they find Stephen on the floor, crying, holding Heidi in his arms. She is dead.

Retired Baltimore County Police Sergeant Allen Meyer was one of the first to arrive at the gruesome and bizarre scene.

Heidi, 24, had been strangled and her throat was slit. Cops go room to room trying to piece together a story. But so much doesn't add up.

"The living room area had truly no furniture there, that was odd in it of itself, and throughout the rest of the house, in looking through it, drawers pulled opened," said Meyer. "In the master bedroom, drawers pulled opened in the second bedroom, but even though the jewelry box was open, all the jewelry was still there."

And on the wall above Heidi's head clue left by her killer: "There was a number 1 written on the wall in lipstick," said retired Baltimore County Police Detective Gary Childs.

Do cops have a serial killer on their hands?

Investigators have a tough road ahead of them. While the gruesome scene is processed. Heidi's body is taken to the medical examiner's office, where an autopsy is done, and her fingernail clippings are taken and tested.

Down at headquarters, a blood-soaked Stephen Cooke is brought in for questioning. It's a good place to start -- the husband or boyfriend is always the first place cops look.

"He was denying any involvement at all and he gave us an account for everything he did that day," said Meyer.

Specifically what he had done that evening. Stephen says around 5:30 he took Heidi home because she had to use the bathroom. He didn't want to wait so he left to run his errands.

"Got his oil changed, got his hair cut, went to Home Depot, fixed his sister's plumbing, went through the tunnel and then came back home," said Childs.

And Stephen has documentation proving it all.

"Everywhere he went he either got a receipt for going or the place where he went had video," said Childs.

"Stephen told us that everything was wonderful between the two of them and they were going to go to Las Vegas to get married," said Meyer.

Then cops learn something that may contradict that.

"There were some plans to be married and I guess during that period of time is when they decided to get these insurance policies," said retired Det. Gary Childs.

Some pretty hefty insurance policies: One on Stephen for $900,000, and one on Heidi for $700,000.

"Of course once we heard about the amount of the policies, yeah, we were a little concerned about that, knowing what we did about their income and how their house was," said retired Sgt. Allen Meyer. "He's working part-time at Lowe's."

Heidi was working as a full-time receptionist.

"When I asked the insurance agent, he said they are planning for their future," said Meyer.

But Stephen Cooke says forget about the insurance policies -- he has information on something much more relevant

"So Stephen proceeds to tell us that there had been some issues," said Meyer.

Issues that could point them in the direction of Heidi's killer. The first troubling incident happened a few weeks before Heidi was murdered.

"Heidi's home alone on the phone with a friend and a man comes to the door and he tells her that he's interested in starting a neighborhood watch program, but she doesn't know him from the neighborhood. He's kind of scary to her," Childs.

"Heidi had actually described the neighborhood block watch guy as a larger light-skinned black male or a dark-skinned maybe Mediterranean white male with black hair. He had his tattoo on his left arm that she drew on a piece of paper for the girls that worked in her office," said Meyer. "She drew it."

And then the very day before the murder, there was this: "Back door seemed to have scratches around the lock," said Childs.

It appeared that someone had been trying to tamper with the basement door lock.

Stephen says that terrified Heidi, so he did something about it.

"He goes to the rental agency and demand that they change the locks for him," said Childs.

Investigators have a lot to follow up on. For now Stephen Cooke is free to go. But cops aren't ruling him -- or anyone else out.

"We let him leave headquarters that night and we just had to continue our investigation," said Meyer.

As the weeks go by and after interviewing about a hundred people, police may have caught a break when they learn about a man named Terry Gilliam.

"I find out that Terry Gilliam worked at the Safeway store with Stephen's sister," said Meyer. "He is a butcher. I'm thinking, OK, I've got a girl whose throat was slit, he's a butcher, natural step would be find out what he was doing on the day of the murder."

Meyer says his suspicions grow even stronger when he pulls Gilliam's time card for the day in question.

"It's all digitized, you know, computerized printout, the day of the 20th, the day of the murder, it's handwritten, and its actually handwritten over again, so I'm thinking OK, I might have my guy," said Meyer.

They arrest Gilliam on another charge and bring him in for questioning.

Ultimately, there isn't enough to charge Gilliam with Heidi's murder, yet. So they let him go, but his name remains at the very top of their list.

Over time, a lot of time, the case goes cold. Meyer is promoted out of the Homicide Division, but never gives up on finding Heidi's killer. Then, 11 long years after she was so savagely murdered, the technology catches up with the police work.

There was something definitely worth another look: Heidi's fingernails, and DNA underneath them.

"It's a male, but it's a mixture. We figured it was some of Heidi's and some of whomever," said Sgt. Meyer.

So with a decade's worth of advancements made in DNA technology, they decided to re-submit the fingernails.

"We got a hit," said Det. Childs.

"I'm hoping it's some guy from South Baltimore, and I get the information and it's this guy Alexander Bennett from Colorado, and I'm thinking Colorado? How could this be?" said Meyer. "So now we have to make sure it's the right guy, so I call out to Colorado. I said 'Describe him to me,' and Heidi had actually described the neighborhood block watch guy as a larger either a light-skinned black male or a dark-skinned maybe Mediterranean white male with black hair, and he had this tattoo on his left arm.

"Anyway, the clerk out in Colorado says 'I don't know if he's a light-skin black guy or a dark-skin white guy,' and I'm like Oh my God. And I said 'Does he have a tattoo?' And she says 'Yeah.' At that point I knew we had our guy. Question is, How do we put Alexander Bennett in Baltimore 11 years ago?"

Sgt. Meyer searches the internal Maryland State Police database, which shows when someone has been stopped by police.

"He was able to come up with a hit that gave Bennett's name and his date of birth, but nothing else, which was kind of weird," said Childs. "There was no indication as to why Bennett had been stopped or who stopped him."

So Meyer and Childs fly to Denver, Colorado to talk to Alexander Bennett. It turns out Bennett isn't your run-of-the-mill guy -- he's a trained opera singer. He attended the Denver School of the Arts and received a scholarship to the prestigious Manhattan School of Music.

"He said when he was in Maryland, he got abandoned by some friends, they were going to a concert and he was kind of living on the street," said Childs.

Living on the streets of Baltimore for about a month, around the time of Heidi's murder. And during that time he was stopped by an officer while trying to walk through the Baltimore Harbor Tunnel.

They tell him exactly why they've brought him in.

"This girl's fingernails were taken at the time of her death, and under her fingernails is your DNA. Now there's no denying that, there's no getting around it."

But Bennett offers up an interesting explanation for that.

"He said that when he was in Maryland, he was at a bus stop one day and a girl came up and was just screaming at him and scratching his face for no apparent reason," said Childs.

"I got kind of scared because I was trying to fight back and I think I hurt her."

Childs then shows Bennett photos of several women, hoping he can pick out that woman from the bus stop. Heidi's photo is included in the mix.

"He picked Heidi out of all these other girls that were in the pictures," said Childs.

Childs then lays down his cards.

"For you to have been in Baltimore at the exact time this occurs, for your DNA to be there, for this tattoo to be on your arm in the exact location that the victim describes and actually drew it, I mean that's just a lot of coincidences."

"That's a profound thing, so you know, that's why I'm concerned."

"You rightly should be. I'm concerned."

"Am I being like charged with anything right now?"

"Well, you're not charged with it right now, but I'm telling you things are not going good."

"That's fine, I've given you all the explanation and I've told you everything and, you know like I said, if we're done here, I mean I have a lot of stuff to do today."

There isn't enough to charge Alex Bennett just yet, but before he leaves, Bennett offers up a character witness.

"Bennett indicates that his friend Grant Lewis could verify that he wouldn't have done this thing," said Childs.

Grant Lewis is a longtime friend and associate of Alex Bennett's. Nine years earlier, three years after Heidi's murder, Bennett and Lewis were arrested for calling in a phony bomb scare at a Colorado courthouse. The motive for their bizarre plot? Pin it on the guy Bennett was living with, so they can steal his car when he goes away to prison.

"As luck would have it he had an open warrant on him for some petty offense, but it was enough to at least get him in," said Meyer.

"Finally Grant Lewis said that yeah, he does recall Alex going to Baltimore and ultimately when Alex got home," said Meyer.

"We were drinking down by the bridge, and he said 'I hurt someone bad,' and I looked over at him and I said I don't want to know. He said 'I think someone's dead.' And then he said 'I knifed someone.'"

With that revelation from Grant Lewis, his friend Alex Bennett is eventually arrested for Heidi Bernadzikowski's murder and is extradited to Baltimore.

Two years later Bennett's buddy Grant Lewis, the star witness for the prosecution, is in town to ready to testify against him.

Grant Lewis is prepared to tell the court that one night while drinking, Alex Bennett confessed to murdering someone in Baltimore. But Lewis will never make it to the courthouse.

While Lewis and the detectives are having bagels and coffee, Bennett is making a move no one saw coming.

"His attorneys came out and said 'He'll tell you everything,'" said Baltimore County Prosecutor Matthew Breault.

In an unbelievable turn of events, Bennett wants to talk.

"In a conversation he had with his mother the night before trial started, she told us later on that she talked to him and said 'If you did this, you have to confess and God will forgive you,'" said Baltimore County Prosecutor Garrett Glennon.

"We took Grant Lewis back to the hotel and we rushed off to the courthouse to hear what was going to be said," said Childs.

With Sgt. Allen and prosecutors Glennon and Breault watching from the other room, Det. Childs sits down once again with Alex Bennett. This time Bennett holds nothing back.

Bennett spells out the gruesome details of the night he murdered 24-year-old Heidi Bernadzikowski. He says after he killed her, in an effort to mislead cops he used Heidi's lipstick to write the number one on the wall. He then went around the apartment trying to cover his tracks.

All before delivering the final assault.

"After I had wiped everything down, I was making sure if she was alive, I didn't know, that's when I had the knife and to make sure she had, cut her throat."

Bennett also admitted to being the neighborhood watch guy and trying to break into the house the day before the murder.

But the question remained. Why did Alex Bennett kill Heidi Bernadzikowski?

"The plan of Baltimore just came up, you know, abruptly when Grant was discussing about receiving money to kill somebody."

The same Grant Lewis who was supposed to be the prosecution's star witness. Bennett says his friend was not only involved, he was the mastermind of their sinister murder-for-hire plot.

Cops pick up Grant Lewis from his hotel and bring him in.

Childs starts by telling him that Alex Bennett just confessed.

"So the good news is you won't have to testify, all right, but there's bad news along with that. Grant, you're in the middle of this thing."

Before Lewis says anything more he wants to know what kind of deal prosecutors are offering. Lewis eventually agrees to talk. Lewis tells detectives it was all part of a bizarre scheme to raise money to open a nightclub. He and Bennett came up with the idea to put an ad online selling themselves as hit men. In the advertisement, they carefully selected the wording. It read: "Professional and discreet housecleaning."

"So somebody contacts you back? What does he say?"

"Something to the effect that he was looking for probably a hit or something. I remember him sending an email where he said 'Well I could pay $5,000 up front and then more afterwards, or something, for a hit,' more or less. Yeah, and that's basically what we were looking for was that first set of the down payment, and then we're good to go after that."

But Lewis says the deal was really a scam. They'd take the money, but no one was ever supposed to get hurt.

"He was supposed to go to Maryland to talk to this guy and pick up some funds for him for what this guy was looking at as a contract murder, but there was not supposed to be any fulfilling or anything. You know, you get their money and then turn them in."

Lewis says that all changed when Bennett went rogue and murdered Heidi. Cops aren't buying it.

But who wanted Heidi dead, and was willing to pay for her murder?

Investigators want to know: Can Alex Bennett identify the guy who hired him and Grant Lewis for the hit on Heidi Bernadzikowski?

He's shown photos of six men. Bennett narrows the six down to two, then he points to one.

"I recognize him as the boyfriend."

Bennett points the finger straight at Heidi's boyfriend Stephen Cooke, the same guy who cried like a baby when he called 911.

"We knew we weren't done, we knew there was more to this," said Meyer. "The whole family knew that somewhere along the line that Stephen Cooke had something to do with this, there wasn't a doubt in anybody's mind."

"When I met the boyfriend, he's like 'I'm gonna leave a key and when I'm gonna drop her off, when she comes in, you gotta make it look like she had an accident. It can't look like she was killed because of the insurance.'"

Remember, there were insurance policies Heidi and Stephen took out on each other a couple of months before she was murdered. Heidi's was for $700,000. Stephen had allegedly promised $60,000 to Lewis and Bennett once the job was done and Heidi was dead.

"They never got a dime," said Childs.

Grant Lewis was arrested for conspiracy to commit contract murder. Alexander Bennett took a plea deal and agreed to testify against Lewis and Cooke.

In the years since Heidi Bernadzikowski's murder, Stephen Cooke seemed to have moved on with his life. He got married, had a child and was working for the government in Veterans Affairs. He also collected a small portion of that $700,000 insurance policy after a legal fight with Heidi's family.

"Ten minutes before he supposed to testify, he gets his attorneys and they strike a plea deal, and he ends with taking about 20 percent," said Meyer. "He didn't want to testify."

It was a small victory in court, but an earthquake was about to hit and Stephen Cooke's world would crumble.

"We followed him. He dropped his son off at the elementary school and once he came out of the elementary school property we arrested him," said Meyer. "That was it for him."

Stephen Cooke was charged with first-degree murder. His defense attorney Tara LeCompte says not so fast. The case may not be as open and shuts as it some would believe.

"The first thing he said to me was 'I did not do this. I had nothing to do with this,'" said LeCompte.

LeCompte says besides Bennett's testimony, the prosecution's case was a circumstantial one. There was an alleged contract killing with no contract.

"The police didn't take that computer that day," said LeCompte.

"The lack of a paper trail was one I think of the most difficult things to do in prosecuting this case," said Matthew Breault. "Their computer was sitting on a table and they didn't actually look at it. It wasn't part of normal police procedure back then to conduct investigation into a computer. And I mean, nowadays that would probably be one of the first things they do."

As both sides prepare for trial, Stephen Cooke allegedly tries to pull off a repeat performance -- this time from behind bars.

"While awaiting trial, Stephen met a cellmate, began to talk to him and ultimately asked him to have Grant Lewis, who was also in the same facility, to have him whacked," said Garrett Glennon. "That cellmate was very helpful. He agreed to wear a wire in jail, and we were able to record Stephen talking about having Grant whacked. So we charged him with witness intimidation and attempted murder.

"That seems to be how Stephen Cooke solves problems."

One year after Cooke's arrest, the case goes to trial. The star witness for the prosecution is Alex Bennett. But there is more: Heidi's friends testify her relationship with Cooke was not the blissful one he described.

"She was thinking about leaving him. She had taken steps such as borrowing money from a friend to rent out a storage facility to take that next step to move out," said Glennon.

The crux of the defense's case? Heidi brought this on herself. Cooke's attorneys allege she had been looking for love online when she met Alex Bennett. He traveled from Colorado to Maryland to be with her. And when he showed up at her door, she rejected him, so he killed her.

So you believe they met over the internet.

"On a chat room this man is professing his love for her. An unrequited love made the most sense out of everything," said LeCompte.

"There was no evidence in fact to support that," said Glennon.

In a bold move, Stephen Cooke takes the stand in his own defense. Cameras are not allowed in the courtroom, but Cooke's testimony is recorded on audio. Cooke says he's surprised to hear other accounts of his relationship with Heidi.

Cooke explains how the large insurance policies came to be.

"We were gonna start a family. We were gonna have children and I wanted to make sure that there was enough money for Heidi in case I died. Heidi then asked me if it was all right if she could get $700,000 worth of life insurance, and I said fine."

Then LeCompte asks point-blank if Cooke had Heidi killed.

"Now Steve, you've heard through testimony that you arranged for Heidi's murder via the internet. Did you do that?"

"Not at all. Not at all. I didn't, I didn't have anything at all to do with Heidi's murder."

"Why are you testifying?"

"I'm testifying because I want my family and friends and I want Heidi's family and friends to know the truth."

The case goes to the jury. They deliberate a day and a half.

"We find him guilty."

Guilty of first-degree murder and guilty of witness intimidation and attempted murder.

It was the news so many had waited so long to hear.

Alexander Bennett, as part of his plea deal, was sentenced to 30 years in prison.

Grant Lewis was found guilty and was sentenced to life in prison.

And Stephen Cooke got life without the possibility of parole, plus another 30 years for trying to have Grant Lewis killed.

"I think he got a fair trial," said Cooke's attorney Tara LeCompte.

Cooke's sister Kim told Crime Watch Daily her brother has been wrongfully accused and evidence left out at trial would have proved that.

For Det. Childs and Sgt. Meyer, they're happy they've helped bring closure after so much time to Heidi's loving family.

Cooke continues to maintain his innocence in Heidi's murder. At sentencing, Circuit Judge Jan Marshall Alexander told Cooke he had no doubts about the jury's decision, calling the murder "one of the most coldblooded, heartless, manipulative, despicable crimes that I have seen in almost 30 years of law."