The union representing 9,800 Los Angeles police officers is accusing state corrections officials of compromising public safety by using computer-based risk assessments to reduce the number of parolees -- and by extension, the state prison population.

In a May 5 letter to Gov. Arnold Schwarzenegger, the Los Angeles Police Protective League said it had "deep concerns" about the Parole Violation Decision Making Instrument (PVDMI), a statistical tool now in use by the state Department of Corrections and Rehabilitation to classify and manage parolees.

Last month, after the governor ordered massive budget cuts, state corrections officials proposed reducing the number of ex-convicts on parole by more than 25% and allowing prison inmates to shorten their sentences by completing rehabilitation programs.

Parolees monitored by the state would be reduced by more than 30,000 from the current 114,000. Sex offenders, inmates convicted of crimes classified as violent or serious, and others judged to be high-risk would continue to be monitored on parole.

Additionally, there are more than 16,725 people on the street in California wanted on various parole violations, including 6,532 in Los Angeles County.

Corrections officials have touted their computer risk-assessment tool as way to identify parolees with a high risk of violence and who need more attention. They maintain that it also allows officials to better identify lower-risk offenders, who parole agents would spend less time monitoring and who might be eligible for targeted programs rather than being put back behind bars.

Scott Kernan, head of operations for the parole department, defended the system, saying it's an effective way of assessing the risk of parolees. He said the system also takes a burden off already overworked parole agents, who can focus their attention on the most high-risk offenders.

But police union President Paul M. Weber wrote he was concerned that the system was primarily being used to save money.

"We are very disturbed that the public safety of Los Angeles residents is now being gamed by bureaucrats in Sacramento, determined to 'save money' by implementing a program to block the return of parolees to prison before the Legislature has approved this approach," Weber said in his letter to Schwarzenegger.

LAPD Deputy Chief Charlie Beck said he also has concerns about the application of the system.

"This has a potential to have a huge impact for us," he said. "You can't keep everybody in jail. But not taking into account the entirety of a parolee's history increases the risk of street violence. Past violence is the best predictor of future. To ignore that is to place the community at greater risk."

The debate comes after a parolee killed four Oakland police officers in March.