A Westchester County grand jury concluded that there was “no reasonable cause” to indict a police officer who shot and killed a college football player in a car outside a bar last fall in Thornwood, prosecutors announced on Monday.

The Westchester district attorney, Janet DiFiore, said the grand jury had heard testimony from 85 witnesses in its investigation into the death of Danroy Henry Jr., 20, a junior defensive back on the Pace University football team who was known as D. J. Officer Aaron Hess of the Pleasantville Police Department fired through the windshield of Mr. Henry’s car, killing him and wounding his best friend from high school, Brandon Cox, 20.

A third Pace player, Desmond Hinds, was in the back of the car. He was not injured.

In a statement, Ms. DiFiore said the grand jury had heard from Mr. Cox and Mr. Hinds and 44 other “civilians” and examined more than 100 exhibits that were admitted into evidence. She also said Officer Hess had testified “without the protection of immunity from prosecution.”

Mr. Henry’s father, Danroy Henry Sr., said, “There are no words to express our disappointment” at the grand jury’s decision.