Many unanswered questions remained last night for homicide investigators who were called in to investigate the suspicious death of a 6-year-old boy in Southwest Philadelphia yesterday afternoon.

The boy, who was not identified, was found unresponsive about 2 p.m. in an apartment in the Bartram Gardens complex, on Eastwick Terrace near Conestoga, police said.

He was taken to Children's Hospital of Philadelphia, where he was pronounced dead at 2:18 p.m., cops said.

Police were called when the boy's parents tried to wake him about 1 p.m. and couldn't, cops said.

The parents also told investigators that the boy had complained of not feeling well Tuesday night, but nothing that alarmed them.

"There's no significant evidence of any kind of abuse that we can see," said Homicide Lt. Philip Riehl.

He said that he was unaware of any Department of Human Services involvement with the family.

Riehl said that his unit was investigating the death because of his age and apparent good health.

"He doesn't appear to be malnourished," Riehl said. "He's actually a pretty big kid. It doesn't make sense, so that's why we're investigating."

Last night, neighbors weren't able to offer any insight into the boy or his family.

Riehl said that they moved in last month. Neighbors didn't know where they lived before.

Police planned to question the parents last night but didn't expect to detain them, Riehl said.

He said that he expected more information today once the medical examiner completed an autopsy to determine how the boy died.

Calls to a DHS spokeswoman were not returned last night.