Investigators said Wednesday they have hit a dead end because Irvin never returned their telephone calls.
Irvin has said he was stopped at a red light Jan. 12 when two men in a truck pulled up next to him and one of them flashed a gun.
A Dallas police report said Irvin was "very afraid." The retired NFL star told police he heard one of them call out his name and mention being a "huge Cowboy fan." He said the pair eventually drove off.
Since then, Dallas police haven't been able to get in touch with Irvin to get more details.
Lt. Andrew Harvey with the Dallas Police Department told Dallas-Fort Worth television station WFAA that investigators want to know what happened.
Irvin's longtime attorney, Larry Friedman, said his client wants to work with police.
Irvin had been traveling and was in Tampa, Fla., for the Super Bowl, Friedman said. He planned to make an appointment with police upon Irvin's return.