COBB COUNTY, Ga. -- Police are trying to uncover the mystery of how a young man's body wound up being found stabbed to death on a metro Atlanta playground Monday morning.

Cobb County Police say their officers were called to an apartment complex at 6660 Mableton Parkway about 7:30 a.m. after a resident saw a person's body lying on the ground not moving.

Investigators have few details so far about a motive or a possible suspect, but said they are working the case as a homicide. All they have released is that the young man appeared to have been stabbed multiple times. A cause of death has not been determined.

11Alive's Faith Abubey spoke to the young man's mother, Kelly Benefield, who confirmed that it was her son, 17-year-old Naseer, who was found stabbed. She said her son had been living in the complex with his grandfather for few days after he moved from Macon to Atlanta.

Naseer's grandfather, Kalem Hasan, told 11Alive when he left the apartment Sunday night to get dinner, his grandson was on the phone with somebody, but he didn't know who.

"He told me, 'Be safe grandpa.' and I said, 'OK', and I went on and left," Hasan said.

When he got back, Naseer and his backpack were gone. He said he got ready for bed and locked the door, because he knew the 17-year-old would have to knock to get let back in, "But that knock never came," he said.

Hasan said he continued with his plan to get up early Monday to take his car for servicing. It was when he got back to the apartment that he knew something wasn't right. "Something told me that I needed to go downstairs and see what was happening."

When Hasan got there, he said police were already clearing the scene, but an officer told him that they had found a young man's body at the playground, lying face down clutching bloody money in one hand. When the officer showed Hasan photos, "I said, 'Oh, that looks like my grandson'."

Hasan said police later confirmed to him that it was Nazeer, thanks to fingerprints, but it still doesn't make sense to him how the teen could have wound up dead.

"Whatever lured him out of there, I just don't know what that could have been," Hasan said.

Hasan believes whoever his grandson was on the phone with may be one of the pieces to the puzzle, but it doesn't make it any less shocking.

"I'm sitting here now just as blank as a piece of paper with nothing to write," he said.