A "major player" in the alleged kidnap and murder of an 85-year-old grandfather in Sydney last month has been arrested and charged with murder, police have said.

Widower Chris Baghsarian, 85, was taken from his home in North Ryde on 13 February, in what police say was a case of mistaken identity. His body was found almost two weeks later near a golf course.

Two men have already been charged in connection with his death and on Wednesday police said they had charged a 23-year-old man with multiple offences including kidnap, murder, and firearms and drugs offences.

"He is not the highest but he is a major player in this matter," Det Chief Insp Andrew Marks told reporters.

"We will allege that he facilitated and recruited others to help in the kidnapping and detention of Mr Baghsarian," he said. "We will also allege that he arranged for people to dispose of Mr Baghsarian's body."

The man, who was arrested at a home in the north-west suburb of Seven Hills early on Wednesday, was refused bail and will appear in court on Thursday.

A 23-year-old woman who was arrested at the same time has been charged with breaching an apprehended violence order but does not face any charges in connection with Baghsarian's death.

Detectives believe up to nine people were involved in the kidnapping and murder, and they will continue to investigate, Marks said on Wednesday.

Local media say the alleged attack may have been aimed at a family with links to organised crime.

In the days after the kidnapping, police made several pleas for those who had taken Baghsarian to safely return him as he had health issues and needed daily medication.

Last week police released CCTV footage of three men near what police say was a "stronghold" in Dural, on the outskirts of Sydney, where Baghsarian was kept after being kidnapped.

Police believe the 23-year-old charged on Wednesday was one of the trio pictured.

Marks said the man was also "physically involved" in the kidnapping.

"He was there at the North Ryde address, and we will allege he conveyed Mr Baghsarian to the stronghold," he said. Police would also present evidence he was "in and around the area" for the 40 hours that Baghsarian was held, Marks added.

Two men, 29-year-old Gerard Andrews and 24-year-old Daniel Stevens, were arrested and charged with kidnap and murder last month, a day after Baghsarian's body was found, and are due to appear in court again in April.