Slain Football Player Demarius Reed -- Police Suspect Robbery to Blame for Death

Cops now think wide receiver Demarius Reed -- who played for Eastern Michigan University -- was shot and killed in his apartment during a robbery gone wrong, TMZ has learned.

A rep for the Ypsilanti Police Department tells us, personal items were removed from Reed's apartment -- leading cops to believe that robbery was the motive behind the killing.

Police claim Reed -- who was found dead this morning -- suffered multiple gunshot wounds.

An autopsy is complete but the results won't be available for some time. So far, no suspects have been arrested.