GARLAND, Texas (AP) — Police in Dallas and a nearby suburb say the weapon used by ex-Utah state trooper Brian Smith to kill himself was the same weapon used in a series of freeway shootings last month that left two dead.

Garland police said Tuesday that preliminary tests show the gun Smith used to kill himself was the same one used to kill 20-year-old Jorge Lopez at a red light in Garland Dec. 22.

Dallas police also confirmed Tuesday subsequent shootings on Interstate 635 in Dallas that same night also match Smith's weapon. Investigators had already used preliminary tests to connect Smith to the fatal shooting of truck driver William Scott Miller, who was killed while driving on the interstate about 10 minutes after Lopez was killed in Garland.

Two other people were shot at on I-635 that night. Neither was hit by bullets.

Smith shot himself in Garland after a brief standoff with police hours after the freeway shootings. He died Dec. 24 after he was taken off of life support.