Christopher Kuhn of Hamilton, N.J. is charged with third-degree murder, homicide by vehicle, retail theft and related charges.
Police said Kuhn was fleeing an area department store with stolen goods early Tuesday afternoon when the crash happened on Route 13.
They said he stole speakers for a television set from a Walmart store and was attempting to get away from the scene with his two-year-old son in the back seat.
Witnesses saw the father place the child in the back seat of the SUV but he didn't strap him in. Instead, police say, the 27-year-old rushed to cover his license plate with a sweater.
"It was more important for Mr. Kuhn to attempt to get away from a misdemeanor retail theft by covering his license plate with his sweatshirt than it was to properly secure his 2-year-old son in his car seat before fleeing at a high rate of speed," said Bob James of the Bucks Co. district attorney's office.
Authorities said Kuhn ran a red light at the intersection of Route 13 and Levittown Parkway.
Fernando Medrano, who had a green light, t-boned Kuhn's Jeep SUV, causing it to collide with another vehicle.
"I tried to brake, but I couldn't," Medrano told Action News. "It was too late. He was moving too fast."
Kuhn's SUV flipped on impact and rammed another car traveling north on Bristol Pike.
The two-year-old child in the SUV was thrown from the vehicle during the collision. The child was taken to an area hospital but did not survive.
Police said Kuhn ran from the scene of the crash, but he was captured by police a short distance away.
"I saw it when the baby flew, and I saw Kuhn run away," said Medrano. "I just can't believe he ran away."
"It's unreal," James said. "How can a dad choose even his own freedom over the health and safety and welfare of his own kid."
Kuhn had a shared custody arrangement with the boy's mother.
"Instead of picking up her child last night at 8 o'clock, she got to go visit her son the last time in a hospital. Her deceased son," James said.
Kuhn was charged and ordered held on $5 million bail.