RIVERSIDE -- The county's top prosecutor filed a lawsuit Tuesday in federal court seeking to prevent the early release of inmates because of overcrowding in state prisons.

Riverside County District Attorney Rod Pacheco was joined by San Diego County District Attorney Bonnie Dumanis and 13 other district attorneys in the suit, which was filed in United States District Court in both San Francisco and Sacramento.

The suit seeks to intervene in other federal lawsuits that led to the appointment of a three-judge panel tasked with recommending solutions to overcrowding, including prison population caps and early release for some prisoners.

"We are pleading our case to let these three judges know that early release would be a disaster to the safety of the public," Pacheco said Tuesday evening.

In May, Gov. Arnold Schwarzenegger signed into law Assembly Bill 900, a prison-reform plan that includes the addition of 53,000 beds to the state's overcrowded prisons, as well as county jails. The $7.8 billion agreement was reached by lawmakers in an effort to prevent the early release of prisoners as well as adding to the rehabilitation of inmates.

"We need to let that plan play out before going to the extreme" of early releases, Pacheco said.

In the lawsuit, the 15 district attorneys asked that no early release of prisoners be ordered until the prison reform has been implemented and its effects can be fully assessed.

It also requests that early releases not be authorized unless there is "clear and convincing evidence" that crowding is violating prisoners' civil rights and that no other action will remedy the violation.

The lawsuit also addresses the potential danger early releases would pose to public safety across the state.

There is the real possibility, Pacheco said, that tens of thousands of prisoners could be released early if a population cap was put into place by the three-judge panel.

Pacheco said he's heard that state prisons currently should house between 125,000 and 132,000 inmates, with the present population being about 170,000.

"There is no question we need more prisons and rehabilitation," Pacheco said.

Should the panel of judges decided to release prisoners early, the plan would be to set free those with the least amount of time remaining on their sentences, Pacheco said. So convicted murderers would not suddenly be going free.

If early releases were forced, Pacheco says Riverside County would be the hardest hit and potentially see the most harm to public safety.

"Riverside County has the largest percentage of prison commitments in the state and the law requires a prisoner be released back to the county which sent him there," Pacheco said.

With the lawsuit now filed, the next step, Pacheco says, is having the motion heard in federal court.

"I think we've moved quickly enough" to prevent anyone from being released early from prison, he said.

Contact staff writer John Hall at (951) 676-4315, Ext. 2628, or jhall@californian.com. Comment at www.californian.com.