The Brooklyn actor who played Johnny Cakes - the gay-fireman lover of a mob capo on "The Sopranos" - killed himself in a holiday tragedy that has stunned family and friends.
The front door to John Costelloe's Sunset Park home was still sealed with police stickers yesterday, more than a week after the rugged 47-year-old actor committed suicide.
Costelloe, a former FDNY firefighter, shot himself in the head in his basement bedroom on Dec. 16, cops and pals said.
"It's beyond me. This is too much for me to handle right now," the actor's dad, Michael Costelloe, 77, said yesterday.
Firefighter and former colleague Matt Dwyer couldn't believe his friend was gone.
"He was a great guy. Everyone's completely in shock," said Dwyer, 37, at Ladder 110 in Brooklyn.
"I saw him three weeks ago when he stopped by, and he seemed to be in good spirits."
Costelloe had a crucial four-episode arc on "The Sopranos" in 2006, playing short-order cook Jim "Johnny Cakes" Witowski.
In the hit HBO series, actor Joseph Gannascoli - a longtime friend of Costelloe's - played mobster and closeted homosexual Vito Spatafore, who fled New Jersey after he was outed.
While on the run in New Hampshire, Vito met Witowski, whose specialty was Johnny cakes, a cornmeal pancake. "Sopranos" writers seemed to take a page from Costelloe's firefighting past and included it in the storyline.
In the show, Vito became attracted to Johnny Cakes once he learned the short-order cook was a volunteer firefighter, before being whacked by his homophobic rivals.
"I was shocked when I heard, and it still hasn't really sunk in," Gannascoli told the Post. "I never detected anything troubling about him. I enjoyed all the time I ever spent with him."
In real life, Costelloe worked 11 years at Ladder Cos. 109 and 110 in Brooklyn before retiring in 1998.
Costelloe's loved ones said goodbye to him Tuesday during a funeral Mass at St. Michael's Church in Sunset Park.
"Sopranos" actors Steve Buscemi and Gannascoli attended the wake and funeral. Buscemi and Costelloe were friends dating back to their pre-acting days in the FDNY.
Costelloe killed himself in the middle of a run in the off-off-Broadway ensemble play "Gang of Seven," which had received sterling reviews - including two printed the day after he died.
"This part he had, I really wrote it for him," said "Gang of Seven" playwright Jim Neu, who cast Costelloe as a fast-talking hustler.
Neu said Costelloe's timing was off in his final shows. But when Neu and the director gently quizzed Costelloe about what was bothering him, the actor didn't open up.
"He didn't seem like the kind of guy who would reach out," Neu said. "There couldn't have been a more supportive and friendly group. If he wanted to reach out to people, we were right in front of him. I wish he did."