TACOMA, Wash. — A lawsuit alleges the Tacoma Police Department failed to protect two children who were sexually abused by a convicted sex offender their mother was dating.

The News Tribune reports (http://bit.ly/2iZjmYJ ) the minors, identified in the civil action as 11-year-old M.E. and 9-year-old J.E., filed the complaint Aug. 23 against the city.

The suit alleges, in part, investigators missed signs of sexual abuse in the home on one occasion and should have known the mother’s boyfriend had been convicted of a prior sex crime when they talked to him on another occasion. The suit says as a result of the negligent investigation, the girls were subject to “repeated acts of sexual assault.”

The police department declined to comment on the lawsuit, refusing to speak about pending litigation.