Sergeant Scott lost his fight with cancer.
When Sergeant Scott died of lung cancer, David Rossi canceled his planned fishing trip with his daughter and grandson and immediately flew to Los Angeles. Once on the West Coast, Rossi paid for a military funeral with full honors. With the help of Penelope Garcia's Internet skills, many of the members of Scott and Rossi’s Vietnam platoon attended the funeral to pay their respects.
At the end of the episode, we saw a flashback of Sgt. Scott giving David Rossi a Purple Heart. Rossi solemnly placed it on Scott’s casket, along with an aged photo taken of their platoon. He walked away with his daughter, hand-in-hand, who showed up to support him.
Season 12, Episode 12 "Anonymous"