Day four of an inquest into the death of Pat Morena heard expert medical opinion on how multiple factors – poor health, drugs, obesity, an intense preceding struggle, as well as the face-down restraint position in which the 34-year-old ultimately died – may have all been contributing factors in his demise.

Professor Johan Duflou, clinical director of the Department of Forensic Medicine, Sydney, told Sutherland Coroner’s Court the level of stimulants in Mr Morena’s system was enough to cause death in some circumstances. 

Bulli arrest death: man had heart trouble

‘‘After saying that, I have seen higher levels than this in people who have died of other causes,’’ Prof Duflou said.

‘‘I suspect that a person who was not on [drugs], not obese, not stressed and not under excited delirium, if held in a restraint position thus described, would not die.

‘‘Certainly [the death] happened in custody...but it’s not the cause of death.’’

Mr Morena, described by police as a ‘‘mid-level’’ supplier of methamphetamine, died outside a block of units in Bulli on November 8, 2012, after he was approached and subdued by two plain-clothed officers.

He had 0.31 milligrams per litre of amphetamine and 3.8mg/l of methamphetamine in his system and 24 small envelopes of methamphetamine secreted in his underwear when he died.  Barrister representing the Morena family, Douglas Marr, suggested it was for fear of police finding the envelopes that Mr Morena  so strenuously resisted arrest.

But Canadian physician Professor Christine Hall pointed to Mr Morena’s apparent tolerance of pain, near-constant physical activity and failure to respond to police (he asked the officers three times in quick succession, ‘‘who the f--- are you?’’) as signs he could be experiencing ‘‘excited delirium’’  before he died. 

The little-understood mental condition leads to abnormal brain activity, resulting in psychosis and sudden death.

Questioned on the likelihood Mr Morena suffocated due to  being restrained face-down, Prof Hall cited her research on about 2000 real-life police use-of-force events, in which a single person,  restrained on their side,  had died.

‘‘Ninety-nine point eight per cent of real-world subjects in a police use-of-force event would be anticipated to survive. 

‘‘Would [Mr Morena] have just died that day [had he not been restrained]? I don’t know. But I think we’re talking about someone who was very, very unwell. His acquaintances described him as grey. When we hear that someone looks grey, that is an...indicator of a bad state.’’

The inquest was adjourned until later this month.