In the documents, officials say Peterson died due to "sudden cardiac dysrhythmia due to hypertensive cardiovascular disease." They note in the docs that "anabolic steroid use" was a contributing factor.

Officials ruled the manner of death as "natural."

He was just 37 years old.

As we previously reported, Peterson -- aka "Da Bull" -- was found dead in October in Orlando ... just before he was set to compete in a top bodybuilding competition.

His coach and close friend Justin Miller said at the time Peterson was in great spirits just before his death, saying the bodybuilder was pumped for the show.

But, tragically, Miller said he found Peterson face down on the floor of his hotel room before the bodybuilder was able to compete. Medical personnel was unable to save him, Miller said.

Peterson was a star on the bodybuilding circuit ... he won the Classic Physique competition at the 2019 Arnold Classic and competed in the Olympia four times.