A man charged with murdering a South Australian police officer has had an unrelated firearm charge dropped.

Jaydn Harley Stimson and his mother, Lynette Stimson, were previously charged with the same offence related to acquiring or supplying a firearm.

The Adelaide Magistrates Court had previously heard the allegations were that Ms Stimson did not transfer ownership of a firearm following the correct procedure and that their firearms licences have since been suspended.

The court previously heard the alleged firearm offence came to light during police investigations into the death of Brevet Sergeant Jason Doig, but was not related to the alleged murder.

Ms Stimson is not charged with the alleged murder of the police officer.

The Adelaide Magistrates Court today heard the charges had been discontinued.

Stimson to face unrelated murder charge

Sergeant Doig, 53, was the officer in charge of the Lucindale Police Station when he was allegedly shot and killed in the line of duty at a rural property at Senior in the state’s south-east in November last year.

At the time of the shooting, Sergeant Doig and two other officers — Sergeant Michael Hutchinson and Constable Rebekah Cass — were responding to what police have described as a report of “the use of a firearm involving an animal”.

Police said Sergeant Hutchinson, who was also shot and sustained non-life-threatening injuries, and Constable Cass provided assistance to Sergeant Doig as well as the alleged shooter, who was himself shot at the scene.

The 26-year-old accused, Mr Stimson, was taken to hospital with life-threatening injuries, and is currently detained at James Nash House.

He is due to face court on murder and attempted murder charges in June.