A New Mexico law enforcement officer admits he looked at pictures of naked women on the internet while on duty, but says he was doing so as part of his job.

The Albuquerque Journal reports that former Bernalillo County Sheriff's Office Sgt. Mark Kmatz filed a complaint for employment retaliation on Wednesday against the Bernalillo County Commission.

Kmatz says he was looking at the naked pictures to research "a specific group of individuals with distinct tattoos and piercings."

Kmatz wrote in the lawsuit that he was forced to resign or be terminated and that the nudes weren't on pornographic sites.

Donald Gilpin, Kmatz's attorney, did not return calls for comment.

Felicia Romero, a Sheriff's Office spokeswoman, declined to comment on the case.

Kmatz had been with the Sheriff's Office since 1997.