'Storage Wars' Darrell Sheets Left Suicide Note, Police Report Reveals

Newly released police records are shedding new light on Darrell Sheets' death ... authorities say the "Storage Wars" star left behind a suicide note and had recently argued with his son.

According to the Lake Havasu City Police incident report, obtained by TMZ, detectives found a handwritten note tucked inside a black basket in a bathroom closet near where Darrell was found dead. Police summarized it as reading, "I could not take anymore the Facebook bulling, f*** you [redacted]" ... adding the handwriting appeared shaky.

The report also paints a clearer picture of Darrell's final night. His girlfriend told detectives he couldn't sleep, got out of bed in the middle of the night, and moments later she found him standing in the doorway of his office ... telling her to "go back to bed" before a single gunshot rang out.

Police also detail family tension in the days leading up to his death. His girlfriend said Darrell's son had recently visited, and the two got into a verbal argument over "family drama" before he left.

She told investigators things only escalated from there ... claiming Darrell later received text messages from his daughter-in-law accusing the girlfriend of being suspicious and stealing money from him, leaving him visibly upset.

In a follow-up interview, she said the arguments with Darrell's son became so heated she left the house at one point because the son was yelling at Darrell. She claimed Darrell told her he didn't want to be alone with his son and had been "sad as hell" after the visit, feeling like he'd let him down.

Investigators also noted Darrell had been battling severe insomnia for months. His girlfriend said he was under tremendous stress and often couldn't sleep, but she insisted he'd never talked about harming himself and described their relationship as strong in the weeks leading up to his death.

As TMZ previously reported, Darrell was found dead at his Arizona home on April 22 after his girlfriend called 911 to report hearing a gunshot. The medical examiner later ruled his death a suicide.

His son, Brandon Sheets, later broke his silence with an emotional tribute ... calling Darrell "the best dad a son could ask for," before announcing he'd reopen his father's Arizona store, Show Me Your Junk, to carry on the family business.

Darrell mentioning online bullying in the suicide note is interesting too ...  fellow "Storage Wars" star Rene Nezhoda claimed Darrell was dealing with relentless online bullying before his death and police investigated the claim.