An inquest has heard police may have missed a chance to seize guns from a South Australian cattle farmer in the days before he was involved in a deadly shootout with elite officers.

Alexander Kuskoff, 50, was shot in the chest and abdomen by a STAR Group officer in September 2015 after a dramatic five-hour siege in Elwomple, in the Murray Mallee.

An inquest into Mr Kuskoff's death, before Deputy Coroner Anthony Schapel, today heard police were trying to detain Mr Kuskoff under the Mental Health Act but the the cattle farmer resisted and fired numerous shot during the stand-off.

Mr Kuskoff' was shot during a siege at his rural property. (9NEWS) (9news)

Counsel Assisting the coroner Andrew Harris said Mr Kuskoff was likely suffering an acute psychotic episode and had threatened to kill numerous people - including police - in the two days prior.

Mr Kuskoff made nearly a dozen triple zero calls, which were today played to the court.

The farmer's sister is representing herself and the family at the inquest.

The deputy coroner was told a police patrol did a welfare check at the property a day before the shooting, but the officer failed to check for firearms that were registered to Mr Kuskoff.

The deputy coroner and counsel assisting at the property. (9NEWS) (9news)

The inquest has also raised questions over whether the STAR officer was under sufficient threat to warrant the shooting and whether the shootout could have been avoided.

The police officer is expected to defend his actions and claim Mr Kuskoff was shooting randomly in the direction of officers and he believed his life and the lives of his colleagues were in danger.