Updated

SACRAMENTO, Calif. (AP) — State parole agents missed numerous chances to send a convicted child molester back to prison before he raped and killed two San Diego-area teenagers, the corrections department said Wednesday.

John Albert Gardner III wore a tracking device for a year before he finished parole in September 2008, but his parole agent did not review the data because he was considered a low-risk sex offender, Inspector General David Shaw said.

The data from the GPS ankle bracelet showed numerous violations by Gardner, including the apparent commission of a new felony by going to a state prison parking lot, the report said.

He repeatedly violated other parole conditions, including getting within 100 yards of places where children gather, that also could have put him back in prison, the report said.

Better monitoring "could have sent Gardner back to prison, making it impossible for him to murder two young girls and commit the attempted sexual assault," Shaw said in his report. "The department did not identify Gardner's crime and parole violations because it did not require parole agents to review the GPS data."

In addition, the public is endangered because the department continues to poorly track 4,500 other sex offender parolees who are not considered high-risk, Shaw said.

After Gardner was released from parole, he raped and murdered 17-year-old Chelsea King and 14-year-old Amber Dubois in San Diego County.

Gardner, 31, pleaded guilty to those crimes and was sentenced last month to life in prison without the possibility of parole. He also pleaded guilty to a separate charge of attempted rape.

Gardner was a registered sex offender off parole and living in Lake Elsinore at the time of the attacks. In 2000, he was released after serving five years of a six-year sentence for molesting a 13-year-old girl.

Matthew Cate, secretary of the Department of Corrections and Rehabilitation, said in a letter to Shaw that the report criticized a parole policy that no longer existed. The department changed its policy in March to more actively supervise even parolees considered less dangerous.

Previously, the movements of lower-risk parolees were reviewed only when they were suspected of a new crime or misconduct. Now agents are required to randomly review their movements for two, 48-hour period each month.

Shaw's report said the new policy, "though improved, remains deficient" because random reviews are unlikely to reveal violations. It still ignores 87 percent of the GPS data collected for lower-risk offenders.

Gardner told the inspector general that he drove to Richard J. Donovan State Prison on July 12, 2008, to drop off and pick up a friend so she could visit a prison inmate.

The San Diego County District Attorney's Office told Shaw's investigators that prosecutors would have charged Gardner with a third strike offense for visiting the prison, potentially sending him to prison for 25 years to life.

The report found Gardner violated at least three other conditions of his parole on a regular basis. The offenses included living within a half-mile of a school, renting a storage facility and leaving his home in violation of a curfew.

In hindsight, Cate said, the answer would be to review every offender's movements every day. But he said it was unclear how this can be done, given limitations on technology and overworked parole agents.

Steps could include setting priorities for which suspicious movements or electronic violation alerts should be investigated or reviewing parolees' movements in higher volume to detect patterns.

(This version CORRECTS CLARIFIES that one charge against Gardner was attempted rape, sted attempted assault. corrects his residence at time of attacks to Lake Elsinore sted Escondido.)