A Hamilton police officer facing a host of sexual misconduct charges involving women connected to his job has resigned.

Though he had said he always wanted to keep his job, Sgt. Derek Mellor, who headed up Hamilton Police Service's human trafficking initiative, sent in a letter of resignation to police Chief Glenn De Caire last week. The resignation was made public at a police act hearing Monday morning. Since he will no longer be a police officer, the resignation means the end of any prosecution of Mellor under the Police Act.

“The chief has received an irrevocable letter of resignation from Sgt. Mellor, with the effective date being Nov. 3," said police prosecutor Marco Visentini.

Hamilton police spokesperson Catherine Martin would not answer questions about why the chief accepted Mellor's resignation for November instead of effective immediately, or if Mellor staying on the police payroll for an extra four weeks allowed him to acquire pension-related benefits.

"The Service will be providing no further comment as Sgt. Mellor remains under investigation by the Province’s Special Investigations Unit," Martin said in an email.

Mellor, a 14-year veteran of the service, pleaded guilty earlier this year to nine Police Services Act charges after engaging in sexual acts and sending lewd messages as well as photos and videos of his penis to sex workers and colleagues. Monday's hearing was supposed to be the start of the sentencing stage of the hearing. It was set to include testimony from Det. Const. David Hartless — who worked with Mellor on the police service's human trafficking unit dubbed "project rescue."

Several women had notified Hartless of Mellor's advances. Hartless was at the police station Monday, but was not part of the hearing. “The testimony of Const. Hartless is not needed now as a result of the resignation," Visentini said.

All of the police act charges against Mellor will be stayed at his next appearance on Nov. 3. Visentini said he would have "further comment" then. Mellor's legal representative Leo Kinahan didn't comment during the proceedings. Mellor did not appear at the hearing.

Pleaded guilty to PSA charges of sex with sex worker, witness

As part of an agreed statement of facts presented earlier this year, Mellor admitted to undertaking a sexual relationship with the mother of a woman whose human trafficking case he was working on. He admitted to engaging in sexual activity with her on the side of a rural road, sending her pictures of his penis and a three-second video of him masturbating.

He also pleaded guilty to sending sexual photos and texts to two women who worked with the human trafficking volunteer organization “Walk With Me,” and pursuing sexual relationships with two sex workers. Mellor also pleaded guilty to having sex with a woman who was a sex worker and a potential witness in a human trafficking case.

More charges surfaced against Mellor last month, alleging a sexual relationship with a woman who was a potential witness in a domestic violence case.

The charges stem from two separate incidents between August, 2000 and November, 2000.

SIU Investigation continues

According to police act documents, it’s alleged that between August 27 and November 30, Mellor was sleeping with a woman who was a witness or a potential witness in a domestic violence case he was investigating.

A second charge alleges that in that same timeframe, Mellor went to the same woman’s home, and acted in a “disorderly manner.” Those charges will also be dropped in November when his resignation becomes official.

A provincial Special Investigations Unit investigation into his conduct, however, will continue. The province’s police overseer launched an investigation earlier this month.

According to the SIU, Hamilton police did not notify them about the charges — even though local police are mandated to do so in Ontario. The SIU is mandated to conduct criminal investigations into serious injury and death incidents as well as allegations of sexual assault in cases involving police in Ontario.