Erik Menendez (R) and brother Lyle listen to court proceedings during a May 17, 1991 appearance in the case of the shotgun murder of their wealthy parents in August 1989.
CNN  — 

Attorneys for brothers Erik and Lyle Menendez, who were convicted of the 1989 murder of their parents, say new evidence shows the convictions and life sentences should be overturned, according to court documents filed Wednesday.

At their high-profile trials decades ago, the brothers did not deny killing Jose and Kitty Menendez, but argued that they should not be convicted of premeditated murder because they acted in self-defense after enduring a lifetime of abuse by their father. The brothers were retried and found guilty in 1996 after a first trial ended with jurors deadlocked.

In a habeas petition filed in Los Angeles Superior Court, the brothers’ attorneys say that a letter sent by Erik to his cousin eight months before the murders shares details of his father’s abuse.

The petition also says Roy Rossello – who was in the Latin boy band, Menudo, in the 1980s – says he was raped by Jose Menendez, who was an executive at RCA Records.

The Los Angeles County District Attorney’s office, which prosecuted the two trials in the 1990s, told CNN in a statement, “We have received the habeas petition in the Menendez matter and it’s currently under review.”

The letter from Erik Menendez to his cousin, Andy Cano, in December 1988 says “Its (sic) still happening Andy but its worse for me now.”

“He’s so overweight that I can’t stand to see him,” the letter says. “I never know when its (sic) going to happen and its driving me crazy. Every night I stay up thinking he might come in. I need to put it out of my mind. I know what you said before but I’m afraid. You just don’t know dad like I do. He’s crazy! He’s warned me a hundred times about telling anyone especially Lyle. Am I a serious whimpus? I don’t know I’ll make it through this. I can handle it, Andy. I need to stop thinking about it.”

The letter was discovered by Jose Menendez’s younger sister and Andy’s mother, Marta Cano, who shared it with journalist Robert Rand in April 2018, who then shared the letter with Erik Menendez’s former appellate counsel Cliff Gardner the same month, the court document says.

A review of court records shows the letter was not presented at either of the two trials, the document says.

Gardner also discovered last year that as part of a documentary, Rossello said in an interview “he was anally raped twice, and orally copulated, by Jose Menendez when Roy was only 13 or 14 years old” while he was in New York City performing shows, the document says. Rossello shared the assaults in a sworn declaration in an exhibit filed with the habeas petition.

The attorneys argue these two pieces of evidence counters prosecutors’ narrative that Jose Menendez was not violent or the type of person who would abuse children.

“In short the new evidence not only shows that Jose Menendez was very much a violent and brutal man who would sexually abuse children, but it strongly suggests that – in fact – he was still abusing Erik Menendez as late as December 1988. Just as the defense had argued all along,” the court document says.

Attorneys are asking the court to either vacate the conviction and sentence against the two brothers, or permit discovery and an evidentiary hearing when they can provide proof, the document says.

CNN has reached out to the two attorneys for comment.

CNN’s Chloe Melas and Cheri Mossburg contributed to this report.