Nicholas Firkus, the St. Paul man who claimed his wife was fatally shot during a home invasion nearly 13 years ago, was sentenced Thursday to life in prison without the possibility of parole for her murder.

The sentence, handed down by Judge Leonardo Castro, came after a Ramsey County jury found Firkus guilty of first-degree premeditated murder and second-degree murder with intent in connection with Heidi Firkus' death on April 25, 2010.

"I maintain to my dying breath my innocence of this crime," Firkus said in front of a full courtroom in the Ramsey County Courthouse before his sentence was read. Though he was convicted of his wife's murder, he said, "it does not diminish the grief I feel from losing her."

Firkus, 40, showed little emotion as he was sentenced. He has been held in the Ramsey County jail since February, when he was convicted after a two-week trial that included testimony from nearly 50 witnesses. Firkus has not formally appealed, but his life sentence could be reviewed by the Minnesota Supreme Court, a court spokesman said.

Prosecutors argued that Firkus killed his wife out of shame and fear stemming from financial problems. They said he had not told her about $18,000 in credit card debt and a foreclosure on their Hamline-Midway home.

Defense attorneys countered that Heidi's death was a tragic accident. They said a shotgun Nicholas had in his hand went off as he struggled with an intruder just inside the front door of the couple's home on W. Minnehaha Avenue. One shot struck Heidi in the back of the head. The second hit Nicholas in the leg, his lawyers said.

Before the sentencing Thursday, Firkus claimed he had not received a fair trial. But Castro said Firkus was represented by "the most skilled defense lawyers in the state," adding, "I'm sure you received a fair trial."

"There are no winners here," Castro continued. "Many lives were left in pain as a result."

In the years after Heidi's death, Nicholas Firkus remarried and had three children. Many who gave victim impact statements Thursday lamented that Heidi, 25, never got to realize her dream of having children of her own.

"She looked forward to being a mother" and wanted to cut back to part-time work to focus on that, said her mother, Linda Erickson, as she held back tears. "She was robbed. We have had to live with a false public narrative of what happened, a narrative concealing the truth. There is a definite relief of having the record set straight."

Erickson called Heidi Firkus "a joyful child of God" who liked camping, biking and hiking and was filled with humor and a loving spirit. Others remembered her for her beautiful voice, charismatic personality and infectious laugh.

Christa Gibbs, who had known her since they met in nursery school, said she has experienced fear, pain and sadness since her friend's death.

"I no longer have the ability to look at others without suspicion," she said.

The case baffled police for more than a decade and had gone cold until 2019, when a St. Paul Police Department sergeant reopened it. With help from the FBI and new evidence, Nicholas Firkus was charged in 2021.

Joel Howells, who met Nicholas after Heidi's death, on Thursday described his friend as a "loving human being" who put others first. He said he believes he is innocent.

Firkus' father, Steve, does, too.

"To the depth of my heart, I know he did not commit this crime," Steve Firkus said. "It is impossible Nick could have done what he is accused of doing. We continue to pray justice can still be done, and that the truth of what happened will finally emerge."

Defense attorney Joe Friedberg argued at trial that prosecutors had not provided direct evidence that Firkus fired the fatal shot. He said the couple's financial problems were not a motive for murder because if Firkus killed his wife, everything would become public.

"He told me his story and I believed it," Friedberg said in court Thursday. "He is a wonderful and sincere human being. There is not a better man you are going to sentence than Nick Firkus."