He was cleaning the streets of pimps and slavery.

Now, Hamilton's first human-trafficking cop is the one facing a slew of sex-related charges.

Sergeant Derek Mellor, a 14-year veteran officer, has been charged under the Police Services Act with 11 counts of discreditable conduct related to his investigations.

Dressed in a suit and tie, Mellor made his first appearance at Central Station Wednesday and waived his plea until the hearing date is set on July 30. Mellor has been under suspension since mid-December.

The charges against him include having sex with two possible female witnesses, sending both sexual photographs and sending one a sexual video. He's also accused of sending sexual pictures to two female employees of a victim services agency and attempting to have an inappropriate relationship with two other women whose role in the investigations is unknown.

The probe against Mellor began in 2012 after a 19-year-old former sex worker, who was a witness in a human trafficking case, accused him of having an inappropriate sexual relationship with her.

The allegations span several dates from May 2011 to the end of 2012. During that period, Mellor's unit laid more than 100 charges, some of them related to human trafficking, against six people.

Defence counsel Mike Cruse of the Hamilton Police Association would not comment on how Mellor plans to plead next month.

"We waived our plea because we haven't had disclosure yet," the lawyer said. "We really can't make an informed decision."

Cruse expects to be presented with the case against Mellor before the end of July. He would not describe Mellor's reaction to the allegations against him.