A witness told authorities that a scuffle broke out between a Virginia State Police special agent and another man before the officer was shot in the head.
That detail was revealed in a search warrant affidavit filed in court after the shooting death of Special Agent Michael Walter last week.
Authorities say Walter and a Richmond officer approached a car May 26 and the Richmond officer detained the driver.
The search warrant says the driver told police he "observed a scuffle" between Walter and Travis Ball, who had been sitting in the passenger seat. The document says the driver saw a gun in Ball's hand near the agent's head and then heard a gunshot.
A Virginia State Police spokeswoman wouldn't say what prompted the scuffle or what words were exchanged.