'Storage Wars' Darrell Sheets' Manner of Death Revealed

"Storage Wars" star Darrell Sheets' manner of death has been revealed ... and officials say he took his own life.

The 67-year-old's tragic death was officially ruled a suicide ... according to the Mohave County Medical Examiner's Office in Arizona.

We broke the story ... Darrell was found dead at his Lake Havasu home last month, and police said it appeared he died from a self-inflicted gunshot wound to the head.

One of Darrell’s "Storage Wars" rivals, Rene Nezhoda, claims people online had been mercilessly cyberbullying Darrell before his death.

Police in Arizona confirmed to TMZ they’re looking into those claims ... telling us, “We are aware of these cyberbullying accusations and that is a part of the active investigation.”