2nd wife's suspicions confirmed with ex-husband's arrest for murder

It was a case that kept St. Paul, Minnesota, investigators up at night as they worked to bring justice to a family for over 13 years.

In the early morning of April 25, 2010, 911 dispatchers received a frantic call from Heidi Firkus, 25.

"Someone's trying to break into my home," Heidi told the dispatcher in audio obtained by ABC News.

An encore presentation of "20/20," "Stranger In The House," airs Friday, March 27 at 9 p.m. ET on ABC. The show, which originally aired in 2023, features the case of Heidi Firkus.

The call ended abruptly with a loud noise. Just 65 seconds later, another call came in -- this time from her husband, Nick Firkus, 27. "My wife is shot, somebody broke into our house," Nick screamed into the phone. "I've been -- shot."

Nick had a gunshot wound to his thigh. Heidi had been shot in the upper back and was unresponsive.

Heidi died at the scene.

In a video interview obtained by "20/20," Nick told police a story of a burglary gone wrong.

Nick said that he awoke to a suspicious noise at his front door, grabbed his shotgun and alerted his sleeping wife.

Nick claimed the gun went off during a life-or-death battle with the burglar and the gun discharged twice -- hitting Heidi, then himself.

"I don't remember exactly what happened, but the gun went off. So my fingers slipped down to the trigger -- went off," Nick told Sgt. Jim Gray of the St. Paul Police Department.

The Firkus house was clean and tidy, and the entryway table beside the front door was undisturbed.

Extensive neighborhood canvassing and a K9 search showed no sign of an intruder.

"He thought he was a Black male, but was not entirely sure," Sgt. Jim Gray told ABC News in an interview.

Nick told Gray that the couple was in financial trouble. They were in over $15,000 of credit card debt, and losing their home.

None of their friends or family knew they were to be evicted the very next day. Investigators found no signs that the couple was packing up for a move.

"It did not look like anybody was planning to go on a long vacation, let alone moving out of the house," Commander Jake Peterson said in an interview with ABC News.

In a review of correspondence between the couple and financial documents found in the home, investigators were unable to find any proof that Heidi Firkus knew of the impending eviction.

Finally, Gray asked the big question: "Did you have anything to do with [the murder]?"

"No," Nick said. "Absolutely not."

Nick retained the services of a defense attorney, Joe Friedberg, who recommended he cease contact with the St. Paul Police Department.

At the advice of his lawyer, Nick declined the SPPD's request to sit down with a police sketch artist to create a composite of the alleged intruder.

"I knew they'd use that as a lever to try interrogating him more. So, I said, no, we won't do that, but we'll hire an artist and do it," Friedberg told ABC News.

Nick and Friedberg returned to the SPPD with their own sketch of the alleged intruder who Nick said was a Black male, in his late 30s and wearing a hoodie.

The police released the sketch through the media to see if any tips would come in. Years later, a woman identified Michael Pye to police as a potential match.

"We started researching him immediately, and we started to learn that he was engaged in a pattern of breaking into homes in St. Paul around six in the morning," Peterson said.

However, Pye was incarcerated on the day of Heidi's murder. Authorities subsequently cleared him of having any involvement in her death.

A few months after Heidi's death, Nick met Rachel Watson.

"I definitely felt sorry for him that he had gone through such a trauma," she said in an interview with ABC News.

After a year of dating, in August of 2012, Rachel and Nick were married.

The couple went on to have three children and moved into a house purchased for them by Nick's parents.

Nick and Rachel had an arrangement where they would pay the mortgage amount to Nick's parents and he would pay the property taxes directly to the county.

Rachel found a notice in their home that stated that they were delinquent on their property taxes, and that their house was in danger of being foreclosed on.

Rachel said her mind immediately went to Heidi's death.

"I didn't know that this was happening, and I'm living with this person. I have children with this person, and the last time he had problems with finances, a lot of things went wrong," she said.

Rachel decided to confront Nick and recorded the conversations.

"The fact that your lying was so easy for you to do in front of me over and over and over makes me think..." she said in one recording.

"That I could murder my wife?" he responded. She replied, "Yes."

The couple divorced in 2018.

In 2019, Sgt. Nichole Sipes of the St. Paul Police Department took a new look at Heidi's death.

"The case always bothered me because the circumstances didn't seem to fit what happened," she told "20/20."

Sipes reached out to the FBI to help reconstruct sound data from the 911 call to see if there was evidence of a third person in the house.

"There was no noise that we could detect in the background," FBI Agent Pat Reilly said.

The FBI also combined their ballistics testing and a virtual model of Heidi and Nick's house to prove that the shots were most likely not "accidental" in the middle of a struggle -- but deliberate.

However, Nick's attorneys countered that these findings didn't necessarily disprove his version of the events.

Once Sipes learned of Nick's recent divorce from his second wife, she reached out to Rachel, who shared her suspicions.

"She could have also been a victim," Sipes said.

In May 2021, Nick was arrested and charged with second-degree murder in the death of his former wife. A grand jury later indicted him for first-degree murder.

Ramsey County prosecutors argued that Nick hid details of their financial troubles from his wife and murdered her due to the shame of their impending eviction.

"It wasn't just going to be the loss of this house, it was going to be the realization that he had lied to his wife, and he had lied to his friends, he had lied to the community for many years," Ramsey County Assistant District Attorney Elizabeth Lamin told "20/20."

Robert Richman, Nick's defense attorney, refuted these allegations.

In addition to the financial evidence, prosecutors also found only Nick's DNA on the gun, and several witnesses testified there were no signs of a break-in.

Nick's attorneys claimed the intruder was wearing gloves and only in the home for a couple of seconds, so he couldn't leave DNA evidence.

On Feb. 10, 2023, after four hours of deliberations, the jury found Nick guilty of murder. He was sentenced that April to life in prison without parole.

His family declined a request from ABC News for an interview but issued a statement in support of him.

"He was wrongfully convicted and sits in jail for a crime he did not commit. This is not just the belief of heartbroken parents," the statement read in part.

In February 2026, the Minnesota Supreme Court upheld Nick's convictions.