California should improve its monitoring of sex offenders, rethink restrictions on where they live and find a better way to evaluate their likelihood of committing new crimes, according to a state panel that investigated the case of an ex-con who pleaded guilty to killing two San Diego County teenagers.

Murder victims Amber Dubois and Chelsea King.

The report by the state's California Sex Offender Management Board concluded that "it is unlikely that a parole revocation for living near a school would have changed the outcome of the crimes" committed by John Albert Gardner III.

"Residing close to a school has not been found by studies to be related to where sexual re-offense occurs," the report found. "At the time of Chelsea King's rape and murder, for example, Gardner was living in Riverside County, but the crimes occurred in San Diego County, nowhere near his home."

Still, the board said Gardner's parole conditions prohibited him from living near a school so he should have been required to move or face the possibility of having his parole revoked.

The 31-year-old registered sex offender pleaded guilty April 16 to murdering Chelsea, 17, and Amber Dubois, 14, both during rape attempts. He had previously served five years in prison for beating and molesting a 13-year-old girl. The board report said electronic monitoring and lifetime supervision should be used for those judged to be exceptionally high-risk offenders, and state law should be changed to create "exclusion zones" prohibiting high-risk offenders from going into parks and other places where children congregate.

"There is no evidence that restricting where sex offenders live will prevent repeat sexual offending against children. In fact, residence restrictions could not have prevented the murder of Chelsea King," the report found.