by KYW's Jim Melwert

Philadelphia police Tuesday morning were still trying to figure out why a man was shot dead in the doorway of his home in Nicetown over the weekend.

The shooting happened just after 2am on Saturday morning in the 1600 block of Staab Street. 43-year-old David Atkins was asleep in his house with his six-year-old son. A man knocked on his door, when Atkins opened the door, that man opened fire, shooting Atkins several times and killing him.

Inspector Joe Moody says Atkins was a single parent working multiple jobs to make ends meet:

"This assault was witnessed by the victim's six-year-old son so it's particularly tragic and disturbing."

Police are hoping someone will come forward with information on the shooter.

Inspector Moody said investigators had no initial motive for the shooting. They say it might be a case of mistaken identity, or a random shooting.