Prosecutors said Tuesday that surveillance videos show two men wearing surgical robes and face masks entering Maldonado's room minutes before he was found dead.
Police recovered one bullet casing from the scene.
Authorities say Maldonado had been kidnapped three years ago and that his kidnappers are currently in prison.
Local media have reported Maldonado was the top hit man for a drug gang in Guerrero state. Police wouldn't comment on those reports.