The Harris County Sheriff's Office in Texas has fired two deputies accused of having sexual relationships with a slain deputy's alleged mistress, a witness to the killing.

Deputy Darren Goforth was shot in the back and killed last August at a Houston-area gas station. The suspect, 31-year-old Shannon Miles, is facing a capital murder charge. He was ruled incompetent to stand trial earlier this month.

Attention is now shifting to the sheriff's department itself, which has fired Deputy Marc De Leon, a 14-year veteran, and Sgt. Craig Clopton. The men are accused of having sexual relationships with a woman who claimed to be Goforth's mistress and was seen crying over his body the night of the killing.

Harris County Sheriff Ron Hickman said De Leon initially lied about his own relationship with the woman, and sources said De Leon was also accused of having sex with the woman while he was on duty.

De Leon's attorney, Joshua Normand, said in a statement, "Mr. De Leon has no comment as to the facts surrounding his separation of employment from the Harris County Sheriff's Office, at this time, as he will avail himself of the appeal process under Harris County Civil Service Rules."

Clopton, who was investigating Goforth's murder, was fired last October because of his alleged relationship with the woman. The Houston Chronicle spoke by phone with Clopton, who declined an interview and asked for privacy, the newspaper reports.

"The leader of any organization would be highly embarrassed for the conduct of an officer that would lead up to termination due to some kind of relationship," Hickman said.

The sheriff's office revealed it's investigating similar allegations against a fourth deputy involving the same woman.

"This one seems to be the gift that keeps on giving," Hickman said, but added that he does not believe the department has a pervasive problem.

The sheriff's office drafted a formal policy last week prohibiting deputies from having relationships with people connected to criminal cases. Hickman said the policy was a direct result of these latest incidents.

It's not the first time the Harris County Sheriff's Department has been plagued by such a scandal.

Three deputies were fired in 2013 for allegedly having sex with a married teacher in their patrol cars, KPRC reports. The woman, a volunteer with the Citizens Police Academy who was married to a reserve deputy, participated in ride-alongs with the department.