BOISE, Idaho (AP) — A southwest Idaho city councilman has resigned from office after admitting to investigators that he was having sex with a 17-year-old girl. Bradley Spencer stepped down Monday in a letter he submitted to the Middleton City Council.

Police arrested Spencer last week and he's been charged with felony sexual battery of a minor. Police say the 56-year-old Spencer told investigators that he knew the girl was underage and that they had been having sexual contact since June. Spencer has been serving on the four-member city council since 2011.

After Spencer's arrest, Middleton Mayor Darin Taylor said Spencer could remain on the council as his case went through the courts. But Spencer instead resigned. Police are investigating whether there are other victims in the case.