A computer algorithm determined that Javier Joseph Rueda would go on nonrevocable probation in January and live unsupervised without risk of incarceration again unless police arrested him for a new crime.

Based on the particulars of Rueda's criminal history, the California Department of Corrections and Rehabilitation's system deemed the parolee a "low threat."

So when Rueda opened fire on Los Angeles police officers (wounding one) earlier this month, critics of California's move toward early release for tens of thousands of convicted felons had fresh evidence that such moves allow dangerous criminals to go free.

This new model of unsupervised parole is one of the first steps in California's effort to reduce its prison population by 40,000 inmates in response to a federal court order to improve health care in the prisons.

And it offers a preview of the difficulty California faces as it struggles to shrink its prison-industrial complex.

The mass release is on hold as the U.S. Supreme Court agreed to consider the order's constitutionality next year.

Following the Rueda shooting, Los Angeles Police Chief Charlie Beck asked the state corrections' department to review Rueda's case and determine if the system fell short. The Los Angeles Police Protection League called for CDCR to scrap non-revocable parole (and digitized decision making) entirely.

But did the formula make a mistake?

Rueda was released Jan. 25, 2009, exactly one year before the parole law took effect, the Los Angeles Times reported*. He'd served two years in prison of a 10-year sentence for several convictions, including auto theft, evading an officer and possession of a controlled substance and a gun silencer.

Nonrevocable parole allows parolees who are not sex offenders, have no violent criminal history and no known-prison gang affiliations to leave prison without risk of being re-incarcerated for technical violations.

Police now contend that Rueda was a gang member.

Gordon Hinkle, spokesman for the state corrections department, said the agency must rely completely on the formula regarding who receives nonrevocable parole. "It's not like our department has a choice on who gets qualified," Hinkle said.

The parole program isn't a policy, but a law enacted by the Legislature and signed by the governor last year.

CDCR had to alter the risk assessment formula in April, The Associated Press reported, returning 656 parolees to supervised parole.

Better documentation of convicts' gang membership could alter who receives nonrevocable parole in the future, Hinkle said. "As we learn about more and more gangs or affiliations, those get added to the list that would exclude somebody from qualifying."

The state has placed more than 6,000 ex-convicts on nonrevocable parole to date.

A federally-funded study of parole in California in 2008 found many parolees are virtually unsupervised. The report, titled "Parole Violations and Revocations in California," argued the system performed poorly as a whole.

"Clearly, this low level of supervision and service provision does not prevent crime. As noted above, two-thirds of all California parolees return at least once to a California prison within three years. Due to their high failure rate, parolees account for the bulk of California prison admissions: In 2006, nearly two-thirds (64 percent) of all persons admitted to California prisons were parole violators. Parole revocations have been rising nationally over the last 20 years, but California's have increased more so. Nationally, over the last 20 years, the number of parole revocations has increased about six-fold. In California, the number of parole revocations has increased 30-fold."

** This sentence originally reported Rueda was released Jan. 25, 2010.