A man detained but never charged in the murder of a Cold Spring police officer is suing Sauk Rapids Police Sgt. Tom Roy for defamation, claiming the officer wrote on a Facebook page that he was likely the killer or a participant in the crime.

Cold Spring officer Thomas Decker was shot in the head outside a bar on Nov. 29, 2012, shortly after making a welfare check on Ryan Larson. The check was prompted by a call from Larson’s mother, who expressed worry that her son was suicidal.

Larson was taken to jail but was never charged with a crime; he was released five days after the shooting. Another man, Eric J. Thomes, was later named a person of interest in the murder but killed himself after a standoff with police a month later.

The suit filed in Benton County court last week claims Roy posted comments on Facebook saying Larson was “likely the killer or a participating witness.” The suit said Roy’s statements wrongly created the impression that he had “engaged in illegal, immoral, criminal or wrongful conduct.” Larson is seeking damages of at least $50,000.

Larson already settled defamation suits with KSTP and WCCO last year.