The 60-year-old bartender was murdered on January 2.
His body was found two days later in the basement at McWhitey's Tavern in Port Richmond.
O'Neill had been beaten to death, and his body wrapped in a tarp.
His sister told Action News that the family is grief-stricken and searching for answers.
Police have issued an arrest warrant for 36-year-old John McLaughlin, the operator of McWhitey's Tavern.