The Fairfax County prosecutor has turned over the investigation of a fatal police shooting of an unarmed Springfield man to federal authorities, citing complications with the five-month-old case.

Commonwealth’s Attorney Ray Morrogh said the U.S. attorney’s office for the Eastern District of Virginia has agreed to continue the probe into the death of 46-year-old John Geer, who was shot during a standoff with Fairfax County police in August. No one has been charged in the incident.

“There is a conflict of interest that has arisen in the case,” Morrogh said Thursday. “And there is a second potential conflict of interest that has arisen out of my office. . . . This is the prudent thing to do.”

Morrogh declined to describe the nature of the conflicts because the investigation is ongoing. The U.S. attorney’s office said Thursday that it could not confirm or deny any investigation or comment on pending investigations.

Police went to Geer’s Pebble Brook Court home on Aug. 29 because of a report of a domestic disturbance. Geer’s father, Don Geer, said his son was upset because his girlfriend, the mother of his two children, had decided to leave him.

John Geer had thrown his girlfriend’s belongings in the front yard. She called police and told them that Geer had a firearm. Police said they tried for about 50 minutes to persuade Geer to leave the home, but he refused.

Don Geer said he watched the climax of the encounter. He said that he could not hear what officers were saying to his son but that he saw him standing with empty hands resting on top of a screen door at the home’s entrance.

At some point, John Geer began to slowly lower his hands and an officer opened fire, hitting Geer in the chest, his father said. Geer retreated inside and closed the door. A SWAT team eventually entered the home and found Geer dead.

Don Geer said detectives later told him that his son did not have a gun on him at the time of the shooting but that there was a holstered handgun a couple of steps from the front door.

Don Geer said it appeared to him that the shooting was unjustified, but he was unsure what to make of the probe being turned over to federal authorities.

“I don’t know whether that’s good or bad — if I had a better idea of why they are doing it, I could form an opinion,” he said.

Geer and friends of his son have been critical of how long the investigation has taken, but Morrogh said police and prosecutors were working to explore all the evidence. He did not think federal prosecutors would have to start from scratch.

“No one wants these things to linger on,” Morrogh said.

Get updates on your area delivered via e-mail.