Two men have been arrested over the "execution-style" killing of an Adelaide man earlier this month.
A 29-year-old man handed himself in on Monday night and was charged with the murder of Simon Middleton.
On Tuesday, police went to an address at Virginia, north of the city, and arrested a 44-year-old man.
He was expected to also be charged with murder.
"Despite the arrests, the investigation is ongoing and police are seeking to determine the role of others, including a man and woman, in the planning of the murder," police said.
Mr Middleton, 49, was found dead outside a property at Virginia.
Detective Inspector Brett Featherby described the death as an "execution-style" killing involving several people.
"The investigation has led us to believe that the premises where Simon was shot had been under surveillance," he told reporters on Monday.
"We are aware that a number of people had been involved in the planning of that murder.
"One man has engaged Simon in a conversation and then another has appeared and shot him."
Detectives have so far searched 15 properties and seized seven vehicles but are not yet ready to reveal a possible motive for the attack.
"We believe we do have a motive ... but we need to keep an open mind," Det Insp Featherby said.
