A man killed Wednesday in a traffic accident in Dacula was identified by police Friday as Thomas M. Martin, 41, Monroe.

For unknown reasons Martin, driving a Mercury, used the grass shoulder in an attempt to pass a tractor trailer on the right on SR 316 East near Harbins Road, Gwinnett County police said. He lost control of his vehicle, struck the tractor trailer and then crossed into the median and oncoming traffic on SR 316 westbound.

Martin then struck the rear axles of another tractor trailer that was traveling in the right lane. With his vehicle disabled from that collision, a fourth vehicle struck Martin’s car.

He was not wearing a seat belt, police said. Prescription drugs may have been a factor in the accident. Investigators are awaiting toxicology results.