A woman linked to a suspected Adelaide drug trade murder has been charged with attempting to pervert the course of justice.
The 37-year-old allegedly approached a witness, amid an investigation into the suspected murder of Robert Atkins, on behalf of a third party in custody, South Australian police said on Sunday.
Mr Atkins, 29, went missing in November 2020 and is thought to have been killed, with his body disposed of somewhere near Orroroo, 275 kilometres north of Adelaide.
"The investigation into the murder of Robert Atkins is ongoing and (the woman's alleged) crime and the subsequent arrests by major crime detectives have occurred as a consequence of that investigation," Detective Superintendent Des Bray said.
It comes after police investigating Mr Atkins' disappearance on Friday recovered more than 100 bullets and ammunition packaging from the Hutt River near Clare after a truck driver reported two people acting suspiciously on a bridge late last month.
"It appears they became spooked on seeing the truck and left the area immediately and then returned a few minutes when they thought there was nobody left to see them," Supt Bray previously said.
"We know they got out of a vehicle and disposed of what we believe to be ammunition and also a firearm which we suspect may have been used in the murder of Robert."
Investigators are confident they know the identity of the couple, saying they expect to interview them soon.
It is believed they were disposing of evidence on behalf of a murder suspect.
The suspected murder of Mr Atkins is thought to have links to the deaths of Trevor King and Jeff Mundy.
Mr King, 41, was found dead at suburban West Lakes in January 2020 with police now believing his death was staged to look like a suicide.
Mr Mundy, 36, was last seen in December 2020. His body has not been found, with police suspecting it was disposed of somewhere on SA's Fleurieu Peninsula.
Up to 15 people are believed to have been involved in the murders and detectives are also checking another 200 drug overdose deaths since 2019 to determine if any more are suspicious.
The woman charged with attempting to pervert the course of justice was granted police bail to appear at the Christies Magistrates Court on August 29.
The offence carries a a penalty of up to four years' imprisonment.
