Twenty-eight-year-old William Millett of Groton was sentenced Thursday in U.S. District Court to 60 months of prison followed by five years of supervised release for having 235 photos and two videos of child pornography on a thumb drive and an email account.

The office of the U.S. Attorney for the District of Connecticut said in a news release that Millett, who was arrested Nov. 7, 2017, and has been detained since, also had “instructional guides related to the sexual abuse of children.”

Officials began investigating Millett because an internet protocol address associated with him had accessed child pornography, the release said. Millett pleaded guilty to one count of receipt of child pornography June 20.

Homeland Security Investigations, state police and Groton Town police investigated the case, which was prosecuted by Assistant U.S. Attorney Jacabed Rodriguez-Coss.

Millett’s arrest and conviction was part of the U.S. Department of Justice’s Project Safe Childhood Initiative, which works to protect children from sexual abuse and exploitation, the release said. For more information on the initiative, visit justice.gov/psc.

To report cases of child exploitation, visit cybertipline.com.