Police restraint "possibly" contributed to the death of Wollongong man Pat Morena, but officers had reasonable grounds to try to detain him on suspicion of drug dealing, an inquest has found.
Police brought Mr Morena to the ground outside a unit block on Gwyther Avenue at Bulli on November 8, 2012, after he resisted arrest.
When police went to roll him over onto his back they saw an "expressionless look on his face" and heard him make gurgling sounds.
Paramedics arrived to find Mr Morena, 34, without a pulse. He was transported to Wollongong Hospital but could not be revived.
In findings handed down on Friday, Deputy State Coroner Hugh Dillon found Mr Morena's death was the result of a combination of factors including drug use, physical exertion, anxiety and agitation, morbid obesity and "possibly some degree of compromised cardio-respiratory function due to forcible restraint by police in the prone position for a short period".
The coroner noted Mr Morena's obese-level body mass index, unusually large abdomen, poor diet and 30-cigarette-a-day habit.
"Although in their statement Mr Morena's parents described him as a 'fit young man' he was, unfortunately, anything but fit," he said.
"In the time leading up to his death, he was so grey and sick-looking that he was using make-up foundation to put some colour on his face. He was obese, had a poor diet, suffered sleep apnoea and was taking large amounts of methylamphetamine."
During the inquest, counsel for the Morena family argued police surveillance of Mr Morena in the lead-up to his arrest did not raise reasonable grounds for them to suspect they would find illegal drugs in his car or on his person.
But the coroner found the officers had reasonable grounds to stop and detain Mr Morena as multiple indicators - including intelligence - made them suspect he was carrying drugs.
"Mr Morena had driven down a driveway where his car was concealed or partially concealed from the road. He kept the engine running. Those facts, taken together, were certainly suggestive that he was down the driveway to meet someone in relation to drug supply," the coroner wrote in his findings.
He further noted that police suspicions "turned out to have been well founded", with $850 in cash found in the ashtray of Mr Morena's car; two mobile phones and a disabled taser device found in a secret compartment of the car; and 24 packages of high-grade methylamphetamine hidden in his underpants.
He said it was "probable" Mr Morena was under the influence of the drug ice when police attempted to detain him.
He noted the opinion of toxicologist Dr Judith Perl, who said ice usage could not be excluded as the direct cause of death, and that Mr Morena's death could have occurred at any time irrespective of restraint.
During the inquest, Senior Constable Brian Rice denied placing extra weight on Mr Morena as he restrained him.
The coroner said it was "difficult to assess" the accuracy of the officer's account.
He said the inquest would shed no new light on a long-running debate about the existence of "positional restraint asphyxia" as a cause of death.
"It may be that a number of factors, including [Mr Morena's] physical fitness, his obesity, the quantity of methylamphetamine he had ingested, plus the agitation and restraint combined in immeasurable degrees at the time, causing cardiac failure. In these circumstances, however, it is impossible to determine exactly who or to what extent the actions of the police contributed to the fatal chain of events."