Tuesday's report from the Pima County medical examiner's office says the dead man was holding a pair of bolt cutters in an underground high-voltage utility vault, and there were cut copper wires near his remains.
The medical examiner says the man died between one and two years before his remains were found May 19.
Tucson Electric Power crews found the body when they opened the manhole to investigate a power fluctuation. The manhole was last opened in 2009.
An identification card for a 51-year-old man was found with the remains, but the medical examiner's office is awaiting DNA test results to verify the dead man's identity.