The Chicago woman convicted for the brutal slaying of a pregnant romantic rival in 2007 says new evidence has emerged that proves her innocence and shows someone else committed the crime.

Marni Yang, now 56, was involved in a love triangle affair with former Bears star Shaun Gayle when his girlfriend Rhoni Reuter and Gayle and Reuter's unborn child were shot dead in a Deerfield, Illinois, apartment.

Police arrested Yang more than a year after the crime after a lengthy investigation uncovered physical evidence and a recorded confession.

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Marni Yang mughots portrait and profile

Marni Yang was sentenced to two life terms for the murders of Rhoni Reuter and Reuter's unborn child. Yang's lawyer says new evidence proves her innocence and points to another person being responsible for the slayings. (Illinois Department of Corrections)

Yang and her attorney, Jed Stone, argued in court Monday that new evidence points to a different suspect. Jurors found Yang guilty of two counts of first-degree murder after just three hours of deliberations in 2011, according to FOX 32 Chicago.

"She started screaming, and I just let her have it."

— Marni Yang, in wiretap confession

Yang has been appealing the conviction for years, but a damning admission in her own words helped put her behind bars.

"I had a hoodie on, OK? I had dark makeup on my face and I had gloves on, OK? When … she opened up the door, that's when I … brought out the gun," she told a friend, who was wearing a wiretap. "And when she saw it, she started screaming, and I just let her have it."

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Rhoni Reuter smiles in undated family photo

Rhoni Reuter, the pregnant girlfriend of former Chicago Bear Shaun Gayle, in this undated family photograph. Marni Yang, another woman involved with Gayle, was convicted of killing Reuter and Reuter's unborn child in 2011 after a brutal home invasion shooting. (Courtesy family via Chicago Tribune/Chicago Tribune/Tribune News Service via Getty Images)

Last year, in a jailhouse interview with ABC 7 Chicago, Yang claimed the confession was phony. In it, she claimed she knew her friend was wearing a wire and made a false confession anyway.

"I believed once the case got into the hands of the legal system it would be clear I did not commit this crime," she said.

In a prior appeal, her defense argued that the recorded admissions had been improperly allowed as evidence. However, Yang made several. Prosecutors said she developed a code phrase that she would share with a friend once the murder had been completed: "Do you want to go to dinner?"

About an hour after the murder, Yang's friend picked up her work phone, a line that was recorded under company policy, and heard the phrase. 

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Shaun Gayle in London

Shaun Gayle of Sky Sports during an NFL game between the Seattle Seahawks and the Oakland Raiders Oct. 14, 2018, at Wembley Stadium, London. (Martin Leitch/Icon Sportswire via Getty Images)

Gayle was a longtime Bears defensive back and part of the team that won the 1986 Super Bowl under head coach Mike Ditka. He met Yang at a 2005 Chicago Bears convention, according to court documents, and what began as a business relationship quickly grew into a sexual one. 

He did not immediately respond to messages seeking comment.

Yang's friends testified that they believed she had an "unhealthy" relationship with Gayle, who had been dating Reuter 17 years at the time of her murder.

Yang told co-workers she'd gotten access to the former NFL player's email account and often complained about messages he received from other women, according to court records.

On one occasion, Yang saw an email receipt for a trip to Europe involving Gayle and Reuter. She canceled the reservation.

When she discovered emails from another love interest, she posed as that woman, mimicking her accent, and "sent e-mails to threaten or deter other women involved with Gayle."

Marni Yang leaves court in handcuffs

Marni Kay Yang, right, is escorted from the Deerfield Police Department to the Lake County Courthouse March 4, 2009. (Jose M. Osorio/Chicago Tribune/Tribune News Service via Getty Images)

After Yang learned Gayle would soon be a father in 2007, another friend testified that Yang talked about killing him. But the plot soon shifted toward Reuter, Christi Paschen, a longtime friend, testified. She told the court that Yang admitted to going to Reuter's apartment building before getting cold feet.

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The day before the murders, Yang spent a night at Paschen's house and asked her to do a tarot card reading "to determine whether she would be successful in killing Reuter."

Paschen urged her to "leave it alone" but did the reading anyway, flipping a card that "indicated achievement of a goal." The friend, however, didn't take the event seriously enough to call police.

Chicago Bears vs New England Patriots, Super Bowl XX

Chicago Bears Ron Rivera (59), Gary Fencik (45), Jim Morrissey (51), Dan Hampton (99) and Shaun Gayle (23) during the 1986 Super Bowl against the New England Patriots at the Louisiana Superdome in New Orleans Jan. 26, 1986. (Richard Mackson /Sports Illustrated via Getty Images)

At 7:50 a.m. the following morning, witnesses reported seeing a small figure in face paint and a wig at Reuter's apartment building. Neighbors heard a scream, muffled bangs and a crash. Prosecutors said Yang used a silencer for the attack and that bank records showed she bought a two-volume book set titled "How to Make Disposable Silencers" two months before the shooting.

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Reuter, seven months pregnant, was shot seven times, including once through the head and twice through the stomach. A forensic pathologist said bullet wounds in her arms showed that she died trying to shield her unborn child from the gunfire.

Prosecutors even said Yang took a trophy – a medical-alert bracelet from Reuter's wrist identifying her as a mother to be.

Yang is serving two concurrent life sentences at the Logan Correctional Center in Illinois.

The Associated Press contributed to this report.