The Special Investigations Unit has laid four sexual assault charges against a Middlesex County OPP officer.

The SIU says they were contacted by the OPP in June about complaints of a sexual nature against an officer by a woman.

The alleged incidents occurred between May 28, 2009 and Dec. 31, 2011.

There were no details as to whether the incidents happened when the officer was on duty.

Following an investigation, OPP Det. Sgt. Todd Amlin has been charged with four counts of sexual assaut.

He was arrested Thursday but the SIU, but released with conditions, including refraining from communicating with the complainant.

He is scheduled to appear in court in January.