Ex-Cedar Hill officer convicted after I-Team investigation uncovered pattern of behavior

An Ellis County jury found a former Cedar Hill police officer guilty of official oppression, more than a year after the CBS News Texas I-Team uncovered his documented history of soliciting women while on duty.

Donald Mercer was sentenced to 300 days behind bars for soliciting sex from a woman he arrested.

Mercer pulled over a 27-year-old woman for DWI in August of 2024, performed a field sobriety test, and then placed her in handcuffs in the backseat of his patrol car, records show.

Texas Rangers investigation uncovered criminal conduct during traffic stop

According to a report by the Texas Rangers, when Mercer reached across her to grab a seat belt, the video showed "the victim kisses the left side of (his) neck." The report said, in the video, "(Mercer) then turns his head toward the victim and kisses her."

Investigators said Mercer later pulled over and turned off all his vehicle's lights and his body camera.

According to their report, a camera in the patrol car captured Mercer asking her, "Do you still have to throw up or pee?"

Investigators said he let her out of the car and can be seen talking to her. They wrote, this is when "the victim stated [he] asked her for oral sex, which she refused."

According to investigators, when they returned to the car, video captured the woman "whimpering" and "passing out several times due to her intoxication."

Ellis County prosecutors told jurors, at one point, the woman let Mercer know she had marijuana in her left pocket. Mercer took the marijuana out of her pocket, but prosecutors say he never booked it into evidence or included it in his report. Mercer later told her it had been "disposed of."

The Texas Rangers' report said Mercer and the woman went on to exchange text messages over the next month, with the woman in one case writing, "You had the nerve to ask me to s*** your c***. You pulled over in the middle of nowhere to get me to do so. You know I can report you?"

Cedar Hill police said that by the time they were notified, they were already investigating Mercer for a separate incident involving a domestic violence call. 

In that case, Mercer admitted to telling the alleged victim he wanted to have sex with her.

Internal affairs probe found multiple policy violations

An internal investigation found Mercer violated four department policies, including dereliction of duty and conduct unbecoming of an officer. It was only during the DWI stop, though, that the Texas Rangers found his behavior to be criminal.

"This was an egregious abuse of power, as the defendant was taking advantage of women when they are in vulnerable states," wrote Ellis County prosecutor Christopher Schwieg.

In the punishment phase of Mercer's trial, another woman testified that Mercer groped her breasts during a traffic stop. Prosecutors said Mercer also turned off his body camera at the time to hide evidence of what he was doing.

According to the Ellis County District Attorney, probation has been denied for Mercer, requiring him to serve the 300-day sentence in the county jail.