The medical examiner says the victim, 33-year-old Quynton Ross, died of a gunshot wound to the chest.
Police say he was found unconscious and unresponsive on Monday on Beach 40th Street between Edgemere Avenue and Boardwalk.
The victim left his house Sunday morning and never returned, investigators said.
His worried mother pinged his cell phone on Monday morning and eventually found the phone on the boardwalk.
Ross's body was found by responding police in a bag in an overgrown area off the boardwalk.
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