GREAT FALLS, Mont. (AP) — A former Montana police chief pleaded guilty Tuesday to distributing child pornography via social media, the U.S. Attorney’s Office in Montana said.

William Daly Harrington, 43, entered his guilty plea before U.S. District Judge Brian Morris, who scheduled sentencing for April 13. A plea agreement calls for three other charges to be dismissed.

Harrington spent about 12 years with the East Helena Police Department and was promoted to chief in April 2019.

After pleading guilty, Harrington was released pending sentencing. He faces a mandatory minimum sentence of five years to 20 years in prison, prosecutors said.

According to the criminal complaint, an FBI agent received a tip from Facebook in September 2020 that an account later determined to belong to Harrington shared a sexually explicit image involving a girl who was about 10 years old.

Further investigation found Harrington shared several images of pornography with another Facebook account, determined to belong to Harrington’s girlfriend, between November 2019 and August 2020. More than a dozen of the images appeared to be photos of minors in their early teens, according to court records.

Additional images were found on Harrington’s cellphone.

He was placed on leave in February after the city learned of a sexual assault allegation against him. Harrington resigned March 5.