NCIS (2003)

S03E16 Family Secret

After an ambulance carrying the remains of a Marine who died in a car accident explodes, the NCIS team is summoned to uncover the truth behind the incident. Their inquiry reveals startling revelations: the DNA of the deceased found in the ambulance doesn't correspond to the Marine's, the explosion was deliberately orchestrated, and the family of the fallen Marine is concealing a significant secret.