HUNDREDS OF PRISONERS in California, USA, who were catagorised as posing a “high risk of violence” were mistakenly included in a programme aimed at easing overcrowding in the state’s jails, according to the state’s inspector general.

A new programme, named “non-revocable parole”, was implemented by the Corrections and Rehabilitation Department in California in January 2010; the new regulations allowed inmates that had served their time and were deemed to pose a very low risk of reoffending to be released without being required to subsequently report to parole officers, reports the San Francisco Chronicle.

Those released under the programme would only be returned to jail if caught committing a crime, the Los Angeles Times reports.

As well as dangerous prisoners being let go, another 1,000 inmates presenting a high risk of drugs and property offences were also released.

The office of Inspector General Bruce Monfross examined the prison records and concluded that of the 10,000 prisoners granted non-revocable parole in the first six months of 2010, more than 1,500 should have been supervised and 456 posed a high risk of violence.

However, the Corrections and Rehabilitation Department said that the report’s conclusions were based on a presumption that the department’s upgrade of its review procedures late last meant that its system had previously been inaccurate.

“The fact that we improved it doesn’t mean what we were using at the time was wrong,” said Lee Seale, the deputy chief of staff.

The computer system used to evaluate the risk posed by any inmate did not consider that inmate’s disciplinary history while in jail, while the Department of Justice database used by the program is also thought to be missing some conviction details.

Spokesperson for the inspector general Renee Hansen said that there had been no attempt to return any of the prisoners released to jail or assign parole officers to them.