In a tearful jailhouse interview with the New York Post, the actor insists he wouldn't have agreed to accompany Armento on a late night raid for prescription drugs if he had known his friend was carrying a gun.
He says, "If I would have known, I wouldn't have allowed him in my car. Imagine, we get pulled over and I get caught with an armed felon in my car. Since I've been in the movies, it would have instantly drawn attention."
Authorities have identified Armento, 48, as the gunman in the slaying of police officer Daniel Enchautegui, who attempted to stop Brancato Jr and Armento from breaking into a Bronx apartment to steal drugs.
The Sopranos star, 29, admits he burst into tears when he read an article about the funeral of the cop because he was pained about the premature death of one of New York's finest.
He adds, "When I saw the picture of his father (at the funeral), it brought tears to my eyes because he looked like one of those old-fashioned men - kind of like my father. I also thought that could have been my father going to my funeral.
"If I had the chance, I would want to meet his family and look them in the face and tell then how sorry I feel about what happened."
Brancato Jr, who had a recurring role as a mob boss on The Sopranos, is charged with second-degree murder.