The parents of the man, Christopher Fitzpatrick, told investigators their son had admitted killing the girl May 28 and burying her near the landscaping business where he worked.
Detectives visited the Highland Lakes, N.J., home of Fitzpatrick's parents last week seeking his girlfriend, Jennifer Barrise, on a domestic relations warrant, according to arrest papers.
Fitzpatrick's parents told investigators their daughter was with their son and Barrise when Barrise, 28, gave birth in a car. Fitzpatrick dropped them off at the couple's home in Lake Ariel, then left with the apparently healthy baby, a police affidavit said.
Investigators said the girl told her parents about the baby and when they confronted their son, he claimed to have dropped off the baby at a hospital. But he later admitted killing the baby, police said.
Fitzpatrick, 20, subsequently led state police to the baby's body, telling them he decided to kill the baby because the couple already had a 1-year-old child and couldn't afford another baby, according to police.
A police officer from Franklin Borough, N.J., told The Times-Tribune of Scranton for Tuesday editions that he helped Barrise give birth to the couple's first child last year after she went into labor and couldn't make it to a hospital.
Sgt. Jeffrey Smith told the newspaper the birth was a "little nerve-wracking" but "everything seemed normal."
Fitzpatrick and Barrise were arrested Friday. They are both charged with criminal homicide and concealing the death of a child. Fitzpatrick is also charged with abuse of a corpse. Online court records do not list an attorney for either of them.
Barrise is charged with homicide because, police said, she knew Fitzpatrick was going to kill the infant and did nothing to stop him.
Barrise's brother talked to ABC affiliate WNEP-TV as his sister was being interviewed by police.
"I just can't believe it. Every time I think of it I just have nothing to say, you know. I get speechless," said Frank Schiavone.
Preliminary hearings were scheduled for Wednesday.
