A man accused of being a “major player” in the alleged kidnapping and killing of grandfather Chris Baghsarian was arrested in his underwear by police in an early-morning raid on a home in western Sydney.

The arrest of the 23-year-old man, and a 23-year-old woman who was also at the Seven Hills address, came a month after two other men – Gerard Anthony Andrews, 29, and Daniel Stevens, 24 – were charged for their alleged role in the incident.

Baghsarian’s body was found after he was taken from his Sydney home before dawn on February 13 in a case of mistaken identity.

Investigators believe the 85-year-old was killed at a makeshift stronghold before his body was dumped on the night of February 14 in Pitt Town, a 30-minute drive away.

His remains were located 10 days later near a golf club in Pitt Town.

Detective chief inspector Andrew Marks told media on Wednesday that firearms, prohibited weapons, ammunition, drugs and electronic devices were found during a search of the Seven Hills residence.

While the arrested woman is facing charges unrelated to Baghsarian’s death, the 23-year-old man has been charged with aggravated kidnapping and murder.

“We’ll allege that he facilitated and recruited others to help in the kidnapping and detention of Mr Baghsarian,” Marks said.

“We’ll also allege that he arranged people to dispose of Mr Baghsarian body.”

Marks added that police will allege the 23-year-old was one of the men seen in  fresh CCTV footage released last week that police said showed three people near the kidnappers’ stronghold in Dural, in Sydney’s outer north.

He added that a blue Hyundai featured in the same footage, which police allege was used to transport the kidnapped grandfather, was later found burnt out near a train station.

Asked how significant the man’s role was, he said: “What we will allege is that he’s not the highest, but he’s a major player in this matter and these offences.”

Chris Baghsarian was snatched from his home in Sydney’s north-west.

Authorities believe the intended target for the abduction was a relative of Sydney businessman Dimitri Stepanyan, who lived on the same street as Baghsarian.

Police suspected the intended target was to be kidnapped in hope of a ransom fee being paid and confirmed reports the figure demanded was $50 million.

Baghsarian’s family described the harrowing ordeal of the kidnapping as a nightmare, remembering him as a devoted father, brother, uncle and grandfather “who would never hurt a fly”.

Marks said half a dozen people involved in his abduction and death could still be at large.

“We believe up to nine people were involved in this … we will continue the investigation to identify (them),” he said.

–with AAP