EXCLUSIVE

Chris Cornell had apparently taken more than Ativan before hanging himself, because we've learned he had fresh track marks on his arm when his body was discovered in a Detroit hotel room.

Sources connected to the investigation tell us ... the track marks were "obvious." The singer had a history of using drugs. The toxicology tests will reveal what drugs were found in Chris' system.

The new information is consistent with our story that Ted Keedick, Chris' longtime house engineer and tour manager, said Chris seemed "high" and "f***ed up" during the concert ... hours before his death.