The Truth About Steven Avery's Ex-Wife

Netflix brought the Steven Avery murder case to the general public's attention with the 2015 documentary series "Making a Murderer." The series delved into the 2007 conviction of Avery and his nephew, Brendan Dassey, in connection with the murder of photographer Teresa Halbach in Manitowoc County, Wisconsin. Avery and Dassey were sentenced to life in prison in the baffling case that the series creators, Laura Ricciardi and Moira Demos, argued had been plagued with incompetence and corruption, per the Daily Beast. 

The documentary had many talking about the complexities of America's justice system, earning the series four Emmy Awards. But it also raised ethical questions about the filmmakers' impartiality, with many contending they left out key evidence used to convict Avery and Dassey, CTV News reported. The documentary prompted Ken Kratz, a prosecutor in the case, to release the 2017 book, "Avery: The Case Against Steven Avery and What Making a Murderer Gets Wrong."

Since then, viewers have been divided into those who believe "Making a Murderer" attempted to sanctify a violent man, as The New Yorker noted, and those who believe Avery and Dassey were wrongly convicted — especially since Avery had already served 18 years for sexual assault before being exonerated following new DNA evidence. Though he was cleared of sexual assault, the case had lasting impacts, including on Avery's marriage. Read on to learn what we know about his ex-wife.

In 1982, Steven Avery married Lori Mathiesen, a single mother of one he had met just months prior. Together, the couple raised Mathiesen's son and went on to have four other children over the course of three years: Rachel, Jenny, and twins Steven Jr. and William, according to Express. In "Making a Murderer," Avery mentioned what attracted him to his ex-wife. "She was pretty. Beautiful, that's what I thought. She had a good head on her shoulders. She was making it on her own," he said, according to the outlet.  

On July 29, 1985, just days after Avery and Mathiesen's third wedding anniversary, Avery became a suspect in the sexual assault of Penny Beerntsen, per The National Registry of Exonerations. Avery was sentenced to 32 years that December. 

With her husband behind bars, Mathiesen was left to raise her five children on her own. "I just can't handle these kids anymore. Between the crying, yelling, talking back and fighting I just can't anymore," she wrote in a letter to Avery, according to Express. In 1988, she filed for divorce. In "Making a Murderer," Avery contended Mathiesen sent him threatening letters during that time. However, court documents show he was the one threatening Mathiesen, per Milwaukee Magazine. "I hate you, you got your divorce now you will pay for it," one letter read. "If you don't brang up my kids I will kill you. I promise. Ha. Ha," he said, per another letter. 

Following her acrimonious divorce from Steven Avery, Lori Mathiesen entered into a relationship with Peter Dassey. The familiar last name is no coincidence or just a common name in Manitowoc County. Peter is the father of Avery's nephew, Brandan Dassey (pictured above), who was convicted of being an accessory to murder in the Teresa Halbach case. This makes Avery's ex-wife his nephew's stepmother, as Bustle reported.

According to Romper, Peter is Avery's former brother-in-law, as he had previously been married to Avery's sister, Barb, who is Brandan's mother. As noted by Bustle, Barb later married Scott Tadych and Peter tied the knot with Lori, who became Lori Dassey. One of Peter's sons from another relationship, Brad, laid things out on his Twitter in 2018. "Just to clear things up, Lori Dassey is married to our dad, Pete Dassey. Lori Dassey IS the ex wife of Steven Avery, which ties me into this whole thing. Just to clear up any confusion. It's nothing new as of recently. They've been married since 1997 now," he wrote.

Avery and Lori's children have largely stayed out of the spotlight. Per Newsweek, they have mixed feelings about their father and admitted being estranged from him. "I grew up without a father for so long that it just kind of feels like I don't have (one)," William Avery said. Avery is currently serving his sentence at Wisconsin's Waupun Correctional Institution.