Investigators said Malone was sifting through trash at a Dumpster when Christopher McEneaney, 16, and Andre Mark, 18, started calling Malone names.

People who knew Malone said he was looking for objects to resell.

Investigators said the pair threw rocks at Malone and he mooned the teens, and they became upset.

“They were offended,” said Upper Darby police chief Michael Chitwood. “That’s why he died because he would dare offend them.”

At some point, police said Malone took off running and tried to hide from the teens.

Police said the teens attacked Malone with a knife and shovel, and then left his body on a ball field.

Police also said evidence showed the teens were proud of the crime, because they saved the knife and newspaper clippings covering the murder. Police said witnesses to the crime who came forward and they were key in tracking the alleged killers.

“I do thank the people who came forward who identified the boys and the police,” said Molly Malone-Munsell, the victim’s sister.

Mark and McEneaney are charged with criminal homicide; first-, second- and third-degree murder; assault; robbery; theft; reckless endangerment; possessing instruments of crime; and conspiracy.

McEneaney is charged as an adult.

Both are being held without bail pending an April hearing.