Police are preparing a report for the Coroner following the death of a 36-year-old Adelaide man at Mambray Creek overnight.
About 7.45pm on Saturday 10 January, police received a report that a man was threatening self-harm and was in possession of a firearm.
Police made a number of inquiries and, just after 8.30pm, the man's car was spotted on the Augusta Highway near Port Pirie.
Patrols did not approach the car, but called in PolAir, who began tracking the vehicle just before 9pm.
Police successfully spiked the car's tyres at 9.30pm and the car came to a stop on the wrong side of the road on the Augusta Highway, Mambray Creek two minutes later.
Patrols blocked the highway and cordoned off the area.
When police approached the vehicle, the occupant was found inside in a critical condition due to a self-inflicted gunshot wound.
Officers immediately began first aid and then paramedics attempted CPR, but sadly the man was pronounced deceased at the scene a short time later.
The man's death is not being treated as suspicious.
Due to the man actively evading apprehension by police, this incident will be investigated as a death in custody.
The Augusta Highway was closed overnight to all traffic while police responded to this incident but reopened at 7am.
