Corrections officials failed to properly supervise convicted sex offender Phillip Garrido and missed opportunities to discover the girl he allegedly kidnapped and held in his backyard for 18 years, a report released Wednesday said.

The review by state Inspector General David Shaw blasted the handling of Garrido's case by the Department of Corrections and Rehabilitation during the decade he was under state supervision after being paroled in a previous rape case.

The report said parole agents were not trained to conduct home visits and did not follow up on information that showed Garrido violated his parole. It also faulted the state's GPS-monitoring system, saying it gives the public a false sense of security concerning the whereabouts of offenders.

Shaw said the GPS system falls short of its potential and recommended developing and implementing a comprehensive monitoring policy.

SLIDESHOW: Missing Girl Found 18 Years Later

Police have said Garrido held Jaycee Dugard captive and raped her in a backyard encampment of tents during a period from 1999 until his arrest in August. He allegedly fathered her two children.

Shaw criticized parole agents for not investigating the clearly visible utility wires running from Garrido's house to the secret compound; not talking to neighbors who might have said something about the children; and not questioning further the presence of a 12-year-old girl during a home visit.

"The department failed to properly supervise Garrido and missed numerous opportunities to discover his victims," the report states.

The corrections department issued a written response saying it agreed to improve the parole system and cited legislation that will become effective next year intended to reduce caseloads among agents.

The total parole population in California is 109,982, with sex offenders numbering 6,782. The state has 2,493 parole agents, the statement said.

Garrido, 58, was under federal parole supervision and required to register as a sex offender when he and his wife, Nancy Garrido, allegedly snatched Dugard outside her South Lake Tahoe home in 1991 when the girl was 11. Phillip Garrido had been convicted in 1977 for kidnapping and raping a 25-year-old woman.

California took over Garrido's supervision in 1999.

As a parolee, Garrido wore a GPS-linked ankle bracelet that tracked his movements, met with his parole agent several times each month and was subject to routine surprise home visits and random drug and alcohol tests.

The Garridos have pleaded not guilty to 29 counts related to Dugard's abduction, rape and imprisonment.

Dugard, 29, was reunited with her family in August, and is living with her daughters and mother in an undisclosed location in Northern California.