REDWOOD CITY -- State prosecutors filed felony child pornography possession charges Thursday against San Mateo County's former probation department head Stuart J. Forrest.

Forrest knowingly had materials that showed children engaged in sex acts or showed their genitals, according to the two counts lodged in San Mateo County Superior Court. Each charge carries a maximum of three years behind bars.

When reached by phone Thursday, Forrest said "no comment" and hung up. It wasn't clear if he had retained an attorney.

Forrest retired from his $140,000 per year job in December under the cloud of a federal investigation into allegations he had child pornography. The probe was led by the U.S. Postal Inspection Service and grew to include the U.S. attorneys office. However, for reasons that remain open to speculation the U.S. attorneys office passed the case to state Attorney General Kamala Harris.

Attorney General spokesman Nicholas Pacilio said he could provide no comment on the case.

News broke of the investigation in late December when law enforcement agents, including the FBI, searched Forrest's county office. That probe was allegedly sparked by some items Forrest received in the mail. But authorities have released almost no information about the allegations.

Forrest was named the county's chief probation officer in April 2009. It was the culmination of a career with the department that began in November 1977.

At the time, he was appointed as probation chief, Judge Marta Diaz said in a county news release: "I've known Stu for a very long time. His modesty and leadership skills are only exceeded by his ability and integrity."

Contact Joshua Melvin at 650-348-4335. Follow him at Twitter.com/melvinreport.