A Pittsburgh police detective has been put on desk duty and faces a preliminary hearing today on the second domestic violence charge filed against him in nine months.

Alphonso C. Sloan, 38, of Stanton Heights, was charged July 13 with simple assault, as was his girlfriend, Yvonne Williams-Hill, 25, of the Hill District.

Police had previously arrested the couple in November.

Detective Sloan, who is assigned to the graffiti task force, is temporarily working in the warrant office to minimize his contact with the public. An internal investigation is under way. He and Ms. Williams-Hill are forbidden by the court from contacting each other.

In last week's incident, Ms. Williams-Hill told police that Detective Sloan slapped her and pulled her out of his vehicle by her feet and legs in the Strip District at Liberty Avenue and 24th Street around 10 p.m.

The argument was sparked, she said, when Detective Sloan left her stranded at Gene's Last Chance Bar in the 2500 block of Penn Avenue, according to a police affidavit.

Detective Sloan told police that he left Ms. Williams-Hill at the bar because she was drunk, but he relented and agreed to take her home. As they argued about him leaving, he said she punched him, hit him with her shoe, closed the door on him and bit him twice, according to the affidavit supporting her arrest.

The affidavit said Detective Sloan admitted to dragging her out of the vehicle by her legs, prompting her to rip off his shirt.

He told police he went to his sister's house, called 911, and then waited for 90 minutes before calling again. He "stated that he would make a report the following day figuring that she would calm down and remember what really occurred and how she had assaulted him," the affidavit said.

A hearing for the couple is scheduled for this afternoon in City Court.

On Nov. 12, Detective Sloan and Ms. Williams-Hill (then listed on a criminal complaint as Ms. Williams) were arrested at her Elmore Square apartment and charged with simple assault.

Detective Sloan told police his girlfriend hit him in the head with a cell phone, causing a cut on his forehead.

Ms. Williams-Hill said Detective Sloan pushed her, causing her to fall into a mirror, which broke and cut her. He told officers that she punched him and threw a mirror at him.

"I determined that both parties should be arrested," wrote Lt. Lori McCartney in her affidavit supporting Ms. Williams-Hill's arrest. "I believe that both parties were involved in a physical altercation, and I was unable to determine who the primary aggressor was. Both version[s] of events were inconsistent with the physical evidence that I observed."

Eight days later, prosecutors withdrew charges against Ms. Williams-Hill.

Determining what happened to Detective Sloan's case is more difficult. There is no record of the charge in the court system, indicating the case might have been expunged.

"They both refused to move forward against each other," said Mike Manko, a spokesman for Allegheny County District Attorney Stephen A. Zappala.

While the DA's records reflect that charges were withdrawn against both parties, Pittsburgh police Deputy Chief Paul Donaldson said Ms. Williams-Hill changed her story at a preliminary hearing against Detective Sloan, and the district judge dismissed the charge.

"She did change her testimony indicating he did not injure her in any way, and the charges were dismissed. She claims she was the primary assailant," Deputy Chief Donaldson said.

An internal disciplinary process against Detective Sloan has gone to arbitration. Deputy Chief Donaldson said he could not disclose the bureau's recommendation.

Deputy Chief Donaldson said he did not have information at his immediate disposal about how many police officers have been arrested in domestic violence incidents. However, he said he is concerned about Detective Sloan's situation.

"The bureau cannot mandate personal relationships. We realize that personal relationships are just that," Deputy Chief Donaldson said.

"The bureau certainly is concerned about domestic relationships that are culminating in violent behavior. We are more concerned because he is an employee of ours."

Neither Detective Sloan nor Ms. Williams-Hill could be reached for comment.