Gwinnett County police hope the man who survived an assault can offer clues to those responsible for shooting and killing his associate. But late Tuesday, no arrests had been made in the case.

The survivor, identified as Thomas Smith, 28, of Powder Springs, told police he and 28-year-old Steven Carden, of Marietta, were walking outside a Norcross-area apartment complex around 7 a.m. Monday when they stopped to talk to two other men, police said. Details regarding why Smith and Carden were at the complex have not been released.

“Then at some point (Mr. Smith) was struck from behind by an unknown object,” Gwinnett police said in an emailed statement.

Officers were called to the Celadon apartments on a report of a “person down,” and arrived to find Carden dead from a gunshot wound. Smith was transported to Gwinnett Medical Center with head trauma, but is expected to survive his injuries, police said.

Police have interviewed Smith and other witnesses. The case remains under investigation.