North Queensland police have been accused of spear-tackling and manhandling an Indigenous man just hours before his death in custody.

The lawyer of Trevor King’s family said officers were told the 39-year-old had a heart condition and had probably taken drugs before “trouncing” him after he left his Townsville home.

Police had been called by King’s wife Regina in the early hours of Saturday morning because he was talking of suicide.

“He’d have had a better chance of survival if she didn’t call the police,” Sydney-based lawyer Stewart Levitt said on Monday.

Levitt said Regina King and friends who witnessed the incident reported that police repeatedly told him he was not under arrest after spear-tackling him, pushing his face into the dirt and straddling his back.

“It appears by the time the police got him into the ambulance he was dead,” he said.

Levitt described it as an “eggshell skull” case and called for police to be better trained to deal with those people who are severely depressed or mentally impaired, as well as Indigenous.

“Subjected to the very rough treatment which has been described and the shock of it all, it is quite foreseeable that a man with a pre-existing heart condition would succumb,” he said.

Police on Saturday were not able to say what caused King to lose consciousness and die soon after he was taken into custody about 1.20am.

“An ambulance was present at that time and despite extensive attempts by police and paramedics to revive the man prior to his transport to Townsville hospital, unfortunately those attempts were unsuccessful,” Chief Superintendent Kevin Guteridge said.

King’s death was being investigated by ethical standards command, under the supervision of the coroner, and Queensland’s Crime and Corruption Commission.

Levitt stressed the extent of police involvement in the incident “must” be covered at an inquest.

He also said it was “extraordinary” Regina King and her children were ordered out of the family home hours after his death because police said it was “a crime scene”.

“How could it be a crime scene? None of these alleged events happened there,” he said.

Readers seeking support and information about suicide prevention can contact Lifeline on 13 11 14.