A Charleston County judge decided Friday to postpone a murder trial amid accusations that an investigator on the case had an affair with a co-defendant's mother.

Detective Charles Lawrence's 11-year career with the Charleston County Sheriff's Office ended when he was fired last week reportedly for violating codes of conduct. He appealed the termination and was later allowed to resign, authorities said.

Prior to his resignation, Lawrence had assisted in an investigation into the August 2012 shooting death of Dominique Grant, 25, outside of a Ravenel nightclub.

Sheriff's deputies charged Reginald Gordon, 24, and Derrick S. Brown Jr., 22, with murder and possession of a firearm in the woman's death. The case was scheduled to go to trial July 28.

Gordon's attorney, Michael DeTreville, on Wednesday filed a motion to dismiss the charges. The court documents alleged Lawrence had a sexual relationship with Brown's mother while investigating the killing and lied to his superiors about it.

Lawrence later admitted to sleeping with Brown's mother as recently as June, the documents said.

Ninth Circuit Judge Roger Young on Friday agreed to postpone the trial pending further investigation into the allegations.

In an interview, DeTreville said the continuance was necessary because Lawrence's affair added a layer to the case that attorneys had not anticipated.

"We're tasked with going back through the file, figuring out where Lawrence was involved in the case and whether his actions - the things that he did, or the things that he didn't do - would be prejudicial to our client," he said.

DeTreville said that prosecutors alerted him to the alleged misconduct shortly after Lawrence's termination.

"They immediately disclosed it to us, and that's what they're supposed to do. We feel like the Sheriff's Office did the proper thing, too," DeTreville said.

Sheriff's Maj. Eric Watson on Thursday said the allegations against Lawrence weren't deemed to be a criminal matter.

State Law Enforcement Division agents weren't investigating the situation as of Friday afternoon, spokesman Thom Berry said.

Reach Christina Elmore at 937-5908 or at Twitter.com/celmorePC.