The cause of death of Paul Mitchell’s son Angus has been revealed, he accidentally drowned in the swimming pool

TMZ has obtained the police report and medical examiner’s report Death of Angus Mitchell The Hawaii incident — and the paperwork — certainly sheds more light on what happened before AM passed away … as well as what happened while trying to save him.

According to the documents, cops say witnesses said Angus was out partying with friends the night before he was found at the bottom of a pool at his Honolulu home…water and never resurfaced.

Long story short… The report says that on January 3rd, the driver showed up at Angus’s house that morning – he was supposed to be picked up and taken to the airport – but Angus was nowhere to be found. After a quick search, the driver discovered Angus in the water … apparently lifeless.

Cops say he went in, groped her, tried to give her CPR — and continued to do the same when first responders arrived … even using a defibrillator.

In the end, life-saving measures failed and Angus was pronounced dead.

Cops say they conducted a thorough investigation and after conducting interviews — the last thing any of Angus’ friends remember was him going to the pool deck alone, not appearing under the influence or acting unusual.

There’s also what appears to be surveillance video — and pictures of Angus in the backyard wading into the water.

As we said … none of Angus’s friends thought anything was wrong with him – they noted that he was on no medication and was apparently fit and healthy.

The only thing witnesses cite in the report is that Angus had been drinking the night before – but it doesn’t sound like anyone is concerned about that amount. In terms of the medical examiner – they say Angus died of accidental drowning … but no mention of toxicology. FWIW, most of the paperwork is also heavily edited.

We broke the story … The day before Paul died, he was posting photos of him and his friends on a date, and he looked as happy as could be. He was the heir to his father’s hair care empire, John Paul Mitchell Systems.

He was 53 years old.