PHOENIX -- A former Phoenix elementary teacher was sentenced Tuesday to three years in federal prison for possession of child pornography.

Barrett Keith Williams, 44, was arrested in October 2006 after authorities found explicit images on his computer, including pictures of grown men engaging in sex acts with boys under the age of 12.

At the time of his arrest, Williams was a teacher at Pendergast Elementary School in Phoenix.

Investigators searched Williams’ computer after learning of his subscription to a billing company known to accept payment for Web sites offering child pornography.

Authorities said Williams admitted to paying to visit the Web sites and possessing child pornography on his computer.

Williams pleaded guilty to possession of child pornography in July 2007. He will serve three years in prison and upon his release, will be placed on lifetime supervised release and will be required to register as a sex offender.

Before teaching at Pendergast, Williams taught at West Side Private School in Glendale and Northwest Community School in Phoenix.