He was a plumber who lived in New Jersey.
Cooper met with an unfortunate end in 1998 when Brian Moser murdered him to steal his name and Social Security number. Cooper's death was discovered by a contact of Sergeant James Doakes during an investigation of Brian Moser's Residence.
Brian's alias allowed him to get close to Dexter Morgan.
Debra: "Your name isn't even fucking Rudy Cooper is it?"
Brian: "Nope...but he died for a good cause."