It was unoccupied, but its registered owner, Anthony Nicodemo, 41, was found nearby and taken in for questioning.
Nicodemo is a reputed mob soldier who was once a bodyguard for convicted crime boss Joseph "Skinny Joey" Merlino. Nicodemo was given a four-year suspended sentence in 2009 for his role in an illegal bookmaking operation run inside the Borgata Hotel Casino & Spa in Atlantic City.
A New Jersey state police affidavit in the Borgata case reported that the FBI considered Nicodemo a "prime suspect" in the 2003 shooting death of John "Johnny Gongs" Casasanto, a onetime associate of former mob boss John Stanfa.
A police source said DiPietro also was affiliated with the mob.
The motive for the shooting was not immediately known.
Outside DiPietro's two-story brick home early Wednesday evening, a pool of blood still was in the middle of the street.
A 33-year-old woman who lives around the corner said she was on the phone at home when she "heard five big bangs."
The woman, who asked not to be identified, said she stepped outside and saw her mailman at the top of the block where the shooting occurred. He yelled at her to call 911, which she did.
Then, she said, she walked to the shooting scene and saw the victim lying in the street next to his truck. There was a small crowd gathered in silence.
She said she did not know the victim, but when asked whether she had heard of Nicodemo, she said: "Do I know him? This is South Philly."
She said Nicodemo's mother and sister live on Iseminger, one block up from the shooting. Police later towed the truck, which had a bullet hole in the driver's door, to be examined for evidence.
A neighbor said DiPietro was divorced with two grown sons.
Another woman who refused to give her name who said she was the sister of a victim of a notorious 1990s mob murder said she was asleep at home when she heard what she thought was someone banging on trash cans. She went back to sleep.
When she got up, she said, she had 66 missed calls and 34 text messages.
Contact Robert Moran at 215-854-5983, firstname.lastname@example.org, or follow @RobertMoran215 on Twitter.