SA man to be charged with twin's murder

A 24-year-old man is expected to be charged with the shooting murder of his twin brother at a house south of Adelaide.

Police say the man drove himself to Christies Beach station on Friday morning and gave details of the incident at the Willunga property.

He was arrested and refused police bail with Detective Chief Inspector Tony Ransom saying he was expected to appear in court on Monday charged with murder.

The dead man was shot in head, his body found inside the house in what Insp Ransom described as an unusual incident.

"The scene wasn't pleasant," he told reporters.

Insp Ransom said other family members were distressed and were being assisted.

He said possible motives for the shooting, including the question of mental health issues, were being investigated.