A Hawera invalid beneficiary found dead on his mother's bedroom floor had a fatal concoction of eight drugs in his system, a two year investigation into his death has found.

Michael Andrew Ralston Wyllie, 38, was discovered by his mother cold and unresponsive on the floor of her bedroom on August 31, 2010.

Coroner Carla na Nagara today ruled the death was an unintentional drug overdose and therefore accidental.

The post mortem found Wyllie had methadone, oxazepam, methylphenidate, morphine, diazepam, codeine, citalopram and amitriptyline in his system.

As a result of the subsequent investigation, two friends were convicted of supplying and administering drugs to him.

Brian Wilson was charged with supplying him with methadone, a class B controlled drug, while Jason Springfield was charged with administering him with morphine and Ritalin when he injected him.

Both men were later convicted.

In her written decision released yesterday, the coroner said Whyllie had a long history of abusing drugs.

His mother had twice before found him collapsed apparently due to his drug taking.

''There is nothing in the evidence before me that suggests he was going to take his own life on August 30, 2010,'' Palmerston North based coroner, Na Nagara, said.

A forensic pathologist determined the death was caused by multiple drug toxicity.

He had a significant medical and mental health history and was  prescribed codalgin, diazepam, zopliclone, citalopram, amitriptyline and morphine by his doctor who saw him monthly for close surveillance and was gradually reducing his medication use.

Wyllie's mother was aware her son was a drug user and an alcoholic. He would sometimes stand over her and take her Ritalin.

Friends and associates who spoke to investigating police said he would take prescribed medication and abused drugs.

They said he had access to both methadone and Ritalin.

Some of the things he did on the day before his death were out of character, the coroner said.

''Notably he gave several people hugs and told them he loved them,'' she said.

Friends spoke about how he seemed unhappy and spoke of suicide in the period before his death.

But the coroners said this behaviour fell short of being evidence that he intended to kill himself.

- © Fairfax NZ News