The unemployment claim filed on Peterson was found during a fraud investigation by a group of state and federal prosecutors, according to The Los Angeles Times.
Sacramento County District Attorney Anne Marie Schubert said it is one of at least 35,000 unemployment claims made on behalf of prison inmates between March and August.
Schubert said the state has paid out at least $140 million in benefits. At least 158 claims have been filed for 133 inmates on death row.
Fox News has reached out to Peterson’s lawyers with a request for comment.
Peterson was sentenced to death in 2005 after being convicted of killing his pregnant wife, Laci Peterson, in a case that attracted national attention. The California Supreme Court overturned Peterson's death sentence in August and ordered a lower court to review his murder conviction to see if he should receive a new trial.
Prosecutors would not say how much money was associated with Peterson's unemployment claim, citing an ongoing investigation.
Schubert said claims were also filed in the names of multiple notorious convicted murderers, including Cary Stayner, convicted of killing four people in Yosemite National Park in 1999; and Susan Eubanks, a San Diego woman convicted of killing her four sons in 1997.
In some cases, prosecutors were tipped off by listening in on recorded phone calls from prison as inmates bragged about how they were gaming the system to collect unemployment benefits.
"Quite frankly, the inmates are mocking us," Schubert said.
He and other prosecutors said the problem was compounded by dysfunction at the California Employment Development Department, which, unlike many other states, does not check unemployment claims against a list of prison inmates.
The fraud is so widespread that prosecutors said they were forced to send a letter to Gov. Gavin Newsom on Monday asking for him to personally intervene.
The Democratic Governor released a statement on Tuesday acknowledging that more needed to be done, according to The Times.
“When we saw evidence of fraud in correctional facilities,” he wrote. “I directed the Employment Development Department to review its practices and to take immediate actions to prevent fraud and to hold people accountable when fraud is not prevented.”
El Dorado County District Attorney Vern Pierson said the governor's office has asked Mark Ghilarducci, director of the Governor's Office of Emergency Services, to intervene.
Prosecutors said most cases involved people outside of prison filing benefits in the names of inmates. In Kern County, home to five state prisons, one address was used to receive benefits in the names of 16 different inmates.
"In my nearly four decades I have never seen fraud of this magnitude," Kern County District Attorney Cynthia Zimmer said.
The Associated Press contributed to this report.