'Suitcase Killer' Melanie McGuire defends innocence from inside prison

For some, it might've seemed like a real-life episode of "The Sopranos."

In 2004, three separate dark green Kenneth Cole suitcases, containing pieces of a dismembered body, were found in and around the Chesapeake Bay, near Virginia Beach, Virginia.

The body was eventually identified as 39 year-old Bill McGuire, an employee of the New Jersey Institute of Technology, who lived more than 300 miles away in Woodbridge, New Jersey. The medical examiner determined that the body had been shot multiple times.

His wife, Melanie McGuire, a fertility nurse and the mother of his two sons, was eventually convicted of murdering him and dumping his body. She was sentenced to life in prison.

Thirteen years have passed since Melanie McGuire's conviction. She's now a 47-year-old inmate at the Edna Mahan Correctional Facility in Clinton, New Jersey, where she claims that she's not only innocent of killing her husband but that his real killer is still out there.

Watch the full story on "20/20" Friday, Sept. 25, at 9 p.m. ET on ABC

For the first time in years, she says she has hope that an explosive new podcast, "Direct Appeal," could help exonerate her. The podcast, hosted by Fairleigh Dickinson University criminology professors Meghan Sacks and Amy Schlosberg questions Melanie McGuire's guilt and suggests that there is evidence in the case that never received the legal scrutiny it deserved.

"After all these years, I still feel hurt. I still feel bothered. Like, how could somebody think that I did that?" Melanie McGuire told ABC News' Amy Robach in a rare interview from prison for "20/20."

Melanie McGuire's story made national headlines in the mid-2000s, when she was charged with first-degree murder and dubbed the "Suitcase Killer" by some in the media. Her 2007 trial became a nationally televised event.

Prosecutors believed that Melanie McGuire's motive to kill her husband came from her desire to start a new life with her lover, Dr. Bradley Miller, a partner at the medical practice RMA Associates, where she worked as a nurse.

Melanie McGuire admitted to having an affair with Miller. She said her marriage to Bill McGuire was not going well and claimed that he was violent. In the early morning hours of April 29, 2004, the day her husband disappeared, Melanie McGuire said that they had a violent fight and claimed that he choked her with a dryer sheet and hit her before leaving the house.

"He probably would have broken my cheek if [the hit] had been a closed fist," Melanie McGuire said. "I looked down and there's my 2-year-old. I grabbed the baby and went to the bathroom right behind me and shut the door. I just wanted to get away from him at that point. He said he was leaving and he wasn't coming back and [that] I could tell my children they didn't have a father."

She said her husband left and that she never saw him again.

The investigation into who killed Bill McGuire began in Virginia but eventually moved to New Jersey. A top priority for New Jersey investigators was determining if Melanie McGuire had ever owned a gun. They searched gun records in the state but found nothing. Then, they looked in Pennsylvania.

"They knew that Pennsylvania was close and a lot of people will go to Pennsylvania for firearms because ... gun laws are more lax," Sacks said. "There's less of a waiting period."

"It turned out that when the record check was done with Pennsylvania, a record came back that Melanie McGuire had purchased a gun," said Patti Prezioso, the lead investigator and prosecutor at Melanie McGuire's trial.

Melanie McGuire said that Bill McGuire had asked her to buy the gun for him since he had a felony conviction from a bad driving record, which barred him from purchasing one on his own. It was the timing of that purchase, though, that really caught the eye of investigators: It happened just two days before Bill McGuire went missing.

Once police honed in on Melanie McGuire as the prime suspect, they began wiretapping her phones. They recorded her calls with family and friends, including Miller, with whom she was having the affair.

When investigators discovered the affair, they approached Miller.

"Dr. Miller was adamant that he had nothing to do with any crime, and he didn't know anything about this. So I think the police said, 'Well, prove it. If you're willing to wear a wire, we'll believe you,'" said Sacks.

Miller agreed to cooperate with investigators and was never charged in the crime.

"We looked very closely at Dr. Miller," said Prezioso. "There was no evidence connecting him to this crime."

Miller eventually testified against Melanie McGuire at her trial.

Another important development for investigators was the discovery of Bill McGuire's car.

After his body was found and detectives notified Melanie McGuire of her husband's death, she told them to look for Bill McGuire's missing car in Atlantic City -- she claimed he had a gambling problem and frequented the city. Police quickly found his car in a parking lot there.

Investigators discovered that the parking lot had surveillance cameras, and they pulled the security footage thinking they had stumbled upon a smoking gun that would show who dumped Bill McGuire's car. At the time, the local media also reported this detail about the parking lot's surveillance cameras.

After seeing this report Melanie McGuire told Miller a story that prosecutors later called preposterous.

Melanie McGuire explained that the night after Bill McGuire went missing, she was becoming angrier at her husband and suspected she knew where he was: Atlantic City. She said in a moment of admitted irrationality she decided to drive down there and look for his car.

"And I'm driving down, and I take the first pass on this, on this highway, and I see a dark sedan, and lo and behold, there it is," Melanie McGuire said.

As improbable as it sounds, Melanie McGuire said she actually stumbled upon her husband's car.

"Once Melanie spots Bill's car from the highway, she decides she's going to move his car," said Shlosberg. "Melanie says in the past, when they're angry at each other, it's a way of messing with each other, I guess you could say."

"It sounds beyond ridiculous sitting here saying it and I acknowledge that... It's the truth," Melanie McGuire told "20/20."

After pulling the surveillance footage from the parking lot, however, investigators were disappointed. The grainy images appeared to show Bill McGuire's car being pulled into a spot, but did not capture who the driver was.

Prezioso said she believed that Melanie McGuire was planting the car in Atlantic City to create an illusion that Bill McGuire was still alive.

"That requires two drivers so certainly that means someone helped her," said Prezioso.

Prosecutors have always maintained that they believed Melanie McGuire likely had an accomplice. They were confident Miller was not involved in the crime but were never able to bring charges against anyone else.

Although detectives did not find what they were looking for on the surveillance footage, they were able to find something curious on Melanie McGuire's statement from her electronic toll payment company, EZ Pass. There were two charges, totaling 90 cents, on her statement that proved she had driven to Atlantic City after her husband went missing. Making matters worse, Melanie McGuire had called the company and attempted to have those charges removed.

"I panicked. I absolutely tried to have those charges taken off because I feared that people would look and think what they ultimately ended up thinking," McGuire said.

When investigators processed Bill McGuire's car, they also found a bottle of the sedative chloral hydrate and two syringes. Through record tracing, they found out that the chloral hydrate was picked up at a Walgreens pharmacy just down the road from the McGuire children's daycare on the morning that Bill McGuire disappeared.

The prescription for chloral hydrate came from Miller's prescription pad.

"Dr. Miller looked at the prescription and he said, 'That's not my signature and it appears to be Melanie McGuire's handwriting,'" recalled Prezioso.

Prosecutors believed that McGuire forged the prescription as she had access to this prescription pad.

Five days after Bill McGuire went missing, investigators said Melanie McGuire made another bizarre road trip, this time to Delaware. She told Miller that she was furniture shopping, according to Prezioso, who said she believes that is when Melanie McGuire drove the suitcases with her husband's remains to Chesapeake Bay.

To drive from New Jersey to the Chesapeake Bay in Virginia requires driving through Delaware, "and the first suitcase turned up the very next day," Prezioso said.

Melanie McGuire denies this, pointing to the fact that there are hundreds of miles between Delaware and Virginia Beach.

"You're talking about hours [of driving] and there isn't enough time," said McGuire.

The circumstantial evidence against Melanie McGuire was mounting by this point, but investigators were still having trouble finding any physical evidence that would link Melanie McGuire to her husband's murder, according to Sacks.

Investigators searched the home for evidence multiple times, checking to see if Bill McGuire had been killed and dismembered there.

"They brought in the luminol, and they also pulled down parts of the walls. They pulled out the piping, pulling floorboards up," said Sacks. "They really turned this place upside down a number of times... They couldn't find any forensic evidence whatsoever to establish this was a crime scene."

"I don't know how you would dismember a body and effectively clean that up," said McGuire.

Although investigators were unable to find physical evidence of murder inside the McGuire's home, they were able to find small pieces of Bill McGuire's flesh -- evidence that would eventually be referred to in the media as "human sawdust" -- from the car.

Prezioso believed the "human sawdust" was the result of Bill McGuire's dismemberment.

"Their theory was that this nurse, who was kind of so meticulous, had somehow just forgotten to wipe the bottom of her shoes, that she accidentally tracked these human sawdust particles of Bill's body from the house to the car," said John Glatt, a true crime author who wrote "To Have and To Kill," a book about Melanie McGuire's case.

On June 5, 2005, authorities arrested Melanie McGuire on first-degree murder charges. She pleaded not guilty.

At trial, prosecutors presented an apparent mountain of circumstantial evidence against Melanie McGuire in Bill McGuire's disappearance and murder.

Melanie McGuire's defense team focused on the lack of physical evidence, insisting it was more likely that Bill McGuire was murdered as the result of his gambling, than at the hands of his diminutive wife.

After a nearly month and a half long trial, Melanie McGuire was found guilty. She was sentenced to life in prison on July 19, 2007.

After re-examining her murder conviction over a decade later, Sacks and Shlosberg, believe Melanie McGuire was wrongfully convicted. https://directappealpodcast.com/

"She didn't fit the profile, I guess, of a murderer," Shlosberg said.

With all of her appeals exhausted, Melanie McGuire said she participated in the podcast hoping that new evidence might be discovered that could lead to her exoneration.

"It was hard. It was reliving it. But this was the first time somebody was basically saying, 'We hear you,'" said Melanie McGuire.

When Bill McGuire's body was found with bullet wounds, prosecutors pointed to the fact that Melanie McGuire had purchased a gun in Pennsylvania just two days before her husband was reported missing.

The podcast hosts and Melanie McGuire herself, raise questions about whether it's even possible the gun she purchased was the murder weapon.

"No one plugged the serial number of my gun into a website to find out what the specifications were," said Melanie McGuire.

"There were five lands and grooves that my weapon was said to have made based on the company's website. The bullets that came out of my husband had six lands and grooves," said Melanie McGuire.

Lands and grooves are rifling characteristics that are machine pressed into the barrel of a gun. When a bullet passes through, its smooth surface becomes imprinted with the same number of lands and grooves as the barrel. Melanie McGuire claimed that her gun could not have been the murder weapon since the numbers of lands and grooves on the bullets that came out of Bill McGuire didn't match the number that the manufacturing website said it had made her gun with.

Prezioso said she has no doubt Melanie McGuire's gun was the murder weapon. "It was a mistake on a gun manufacturer's website. We were not gathering evidence from a gun manufacturer's website. The evidence that was at trial was from ballistic experts."

"The evidence in this case points to a well-organized, meticulously planned execution of a murder," Prezioso said during the trial.

Prosecutors also pointed to Melanie McGuire's supposed internet searches in the days leading up to Bill McGuire's disappearance.

They recovered searches including: "How to purchase guns illegally," "How to commit murder," "Undetectable poisons" and, generally, how to sedate or kill someone, according to investigators.

"I'm a nurse or I was a nurse, and I don't need to look up things like that. If I wanted to look for something like that, I have a [physicians' desk reference]. I have a book that I can look in that doesn't leave an internet history," Melanie McGuire told "20/20."

Her defense attorneys argued that anyone could have conducted the searches.

Prezioso said the evidence presented by the state's computer forensic expert at trial was robust and Melanie McGuire's legal team presented their own expert as well. She adds, "Is she trying to say that the man who was so excited to be buying this house, because he wanted to have this house for the wife that he loved and his children, that at the same time trying to kill her? It never made sense."

Investigators also found trash bags in Melanie McGuire's home that they believed matched those used to wrap parts of Bill McGuire's body.

Sacks and Shlosberg claim that the tests run by the state's plastic expert were not sufficient to conclusively link the bags found in Melanie McGuire's house and the ones used to wrap Bill McGuire's body.

"He ran tests, but he didn't do all the tests that you actually need to definitively say whether these bags match," added Sacks. She said that they believe the garbage bags were a prop to sway the jury.

However, the state's expert disagreed, testifying that he ran the tests he believed were necessary to link the bags.

The podcasters and Melanie McGuire also point to unexplained animal hair found on Bill McGuire's dismembered body and noted in investigative reports.

"They looked high and low to connect Melanie to some pet, and once they found that there was no way to connect Melanie to these pet hairs, it became not of evidentiary value," said Sacks.

Sacks firmly believes that prosecutors failed to answer key questions in the case.

"Melanie did not incapacitate, shoot [or] use a saw to dismember her husband," said Sacks. "Do you know how hard it is to cut through bone? It is physically exhausting. Also if the crime scene didn't happen [at the family home] and she's home with her children all night, where is this happening? There are just too many holes in this story."

Prezioso is certain that Bill McGuire's murderer is the woman who was convicted and is now sitting in prison.

"There are times when podcasts and media can shine a light on certain cases where what the government did was not right. This is not one of those cases," said Prezioso.

"My job is not to convince the world. My job is to convince the jury. I believe that the evidence presented to the jury told the jury what happened," Prezioso said.

Melanie McGuire, who is not eligible for parole until she is 101 years old, said the hardest part is not being there for her children. The court awarded custody of her two sons to Bill McGuire's sister, Cindy Ligosh, and Melanie McGuire has had no contact with them since her trial.

McGuire had a message for her sons, who are now adults, "Make up your mind. Don't accept what you're just being told on the surface. Dig, dig. These documents exist. This stuff exists. It's out there," she said.