Drew Peterson wrote "incriminating" jail-house love letters about the death of Kathleen Savio and the disappearance of Stacy Peterson, but those letters were destroyed in a 2010 house fire, the woman he wrote to told ABC News.
Peterson, 58, is currently on trial for the murder of Savio, his third wife, who was found dead in her bathtub in 2004.
Savio's death was initially ruled an accident, but after Peterson's fourth wife, Stacy Peterson, disappeared in 2007, Savio's body was exhumed as part of the investigation and the cause of her death was changed to homicide. Peterson was then charged with murder.
Peterson has denied wrongdoing in both of his wife's cases.
Diana Grandel, 40, the woman whom Peterson wrote love letters to while in jail, told ABC News that some of Peterson's letters, including the ones that dealt with details of Savio's death and Stacy Peterson's disappearance, burned in a house fire in 2010.
"Some of the things Drew and I talked about, a lot of the letters that are more incriminating to him, burned in the fire when my house burned down," Grandel said. " He told me that (Stacy) took nothing with her, and in another interview he said she took bikinis and a purse. But he offered me the bikinis, the purses, the clothes, he offered me all of it. Everything, you name it, he offered it to me."
"I don't .....believe it for a second," Grandel said about Peterson's claim of innocence.
Grandel exchanged steamy letters with Peterson while he was in prison, rekindling a relationship that had begun when she was a teenager and he a Bolingbrook, Ill., cop 17 years her senior. Grandel would not elaborate on their relationship when she was younger.
"I lost touch with him when I turned 18 and I got a serious boyfriend. I wasn't into hanging out with cops anymore, so I lost touch. When I heard he got in trouble my first thought was, you know, I need to support this guy. This just is not him, it couldn't have happened this way," she said.
In the letters obtained by ABC News, Peterson told Grandel he loved her and asked her for detailed descriptions of her body and explained what he would do with her in bed once he was out of jail.
"My love, no one on the planet has been lied to or used more than I have," he wrote in one letter."YOU ARE MY ONE AND ONLY ROMANTIC INTEREST. Sweetie you need to understand that I am a fun loving guy and sometimes I can't stop the obnoxious things that come out of my mouth."
"I have an idea," he wrote in another letter, dated April 15, 2010, "Don't ask questions, just answer mine. OK. Where are you staying? How long will you be there? Tell me your sizes, HEIGHT - WEIGHT - BODY MEASUREMENTS - SHOE SIZE - BRA SIZE."
The two wrote letters for more than six months, but stopped after Grandel began to suspect that Peterson was not telling the truth about what happened to his wives. In 2010, Grandel's house caught fire, taking with it some of Peterson's letters and all of Grandel's belongings. Peterson then offered Grandel the clothes of his ex-wife Stacy.
"After he offered to give me Stacy's clothing when my home burned down, I had a change of heart," Grandel said.
After having been moved by her insurance company to a hotel room and then a new apartment, Grandel said she missed her home so badly that she began to believe that Peterson's story about Stacy taking off from their home without a word in 2007 could not have been true.
"I thought, there's no way this girl walked away from everything for no reason. And I thought, this guy killed Stacy, and I thought I didn't want anything to do with that, so I told him I didn't want to speak with him anymore because my opinion had changed," she said.
Grandel hasn't spoken to Peterson since August 2011.