SALEM, Ore. -- The mother of an inmate who killed himself last year has filed a wrongful death lawsuit against the Oregon prison system.

The lawsuit filed in Marion County by Mary Ayala of Salem seeks $400,000 and is the third such suit in the past week. All three suicides were committed by men 25 or younger.

Prison officials declined to discuss any of the lawsuits, citing pending litigation.

Jeremy Ayala, 25, hanged himself exactly one year ago Friday. According to the lawsuit, he had been on a suicide watch in the disciplinary segregation unit at the Oregon State Correctional Institution in Salem. He had been serving a 15-month sentence for being a felon in possession of a weapon.

The lawsuit says Ayala had a history of depression and poor behavior, and had been having nightmares after his pregnant girlfriend died from a drug overdose in Hood River.

"Every day is hell for me. I just want it to stop," the inmate wrote in a letter that arrived at his parents' house the day he killed himself. The lawsuit alleges that prison employees left Ayala unattended for about eight hours before he was found in his cell during a routine check of all prisoners.

Mary Ayala said she hopes the lawsuits lead to increased monitoring of prisoners with mental illness.

"I want them to pay more attention to the people that are in that kind of situation," she told the Statesman Journal newspaper. "If they were paying more attention to them, there wouldn't be so many suicides in the prison system."

Two lawsuits filed last week are seeking $3.2 million in damages for the estates of Nathan Bashaw, 21, and George William Miller, 18. Bashaw killed himself July 18 in the Special Management Unit of the Snake River Correctional Institution in Ontario, which houses inmates with acute psychiatric problems.

Miller committed suicide March 14 while confined to a cell in the Disciplinary Segregation Unit of the Two Rivers Correctional Institution in Umatilla.