In the dead of night, an undercover Thornton Police Department unit quietly followed a car with missing plates out of Thornton and into Denver and Lakewood.

No lights. No sirens. Unmarked trucks. Mile after mile.

The officers — each a member of the city’s IMPACT team — communicated to one another on the radio.

“Coming up on 6th, going over the bridge,” an officer said.

“You guys want me to take that turn with him?” another asked.

Minutes later, an officer reported a bullet whizzed by his car near the intersection of Alameda Avenue and Sheridan Boulevard.

“Shots fired! Shots fired,” yelled another officer.

At Second Avenue and Garrison Street in Lakewood and with their lights and sirens finally on, the team initiated what’s known as a PIT maneuver. Seconds later, its members shot and killed two people – one unarmed – as the two attempted to jump out of the driver’s side door of the wrecked car.

“My son was stalked that night,” the mother of the unarmed man shot and killed by Thornton officers told 9NEWS Investigates after she reviewed GPS data recorded in the officers’ unmarked trucks.

“We want answers,” Deanine Vigil added.

Her son, Joby Vigil, was 31.

The April 30 pursuit was the third time in less than a year a quiet pursuit initiated by the IMPACT team ended in violence well outside of the primary jurisdiction of the unit.

For more on this story, and others, visit The Denver Gazette’s news partner, 9News.