Clavond Gallot, 40, of the 2200 block of Edgley Street faces murder and related charges in the death of Joshua Gallot.
It happened Saturday at Gallot's home in the Strawberry Mansion section of the city.
Police say the incident occurred around 6:45 a.m. when Gallot called 911 saying he found the 11-month-old unconscious in the bedroom.
Joshua was rushed to Temple Hospital where the baby boy was pronounced dead a short time later.
The exact circumstances of Joshua's death have not yet been released.
The boy's mother, 37-year-old Karen Brown, was not home at the time, but Joshua's 3-year-old sister Danika was.
Brown is the mother of Joshua, Danika, and four other children, and she says she has spent the last three weeks at a girlfriend's house after alleging Gallot, her boyfriend and the father of the two young children, was physically abusive to her.
Brown's aunt, Dahlia Thompson, got the call from police Saturday morning about Joshua's death.
"I think he just snapped because he'd been with them for three weeks while she was gone," Thompson said.
Both Brown and Thompson say they heard little Danika blame her father for her brother's death, adding police described the baby's deadly injuries.