St. Joseph County Coroner Mike O'Connell says 19-year-old Robert Perez died over the weekend.
O'Connell said he had severe head trauma.
The crash happened earlier this month at Ireland and Linden roads.
Investigators say Trooper William Ennis, known as Ben to friends, hit the other car.
Police say Ennis had his lights and sirens on at the time. He was treated and released from the hospital. He has a broken ankle.
The 20-year-old passenger in the car is expected to be OK.