Police have released "confronting" and "disturbing" CCTV footage in a renewed appeal for information about the suspected murder of a man from north-west Sydney.

Brendan Vollmost, 23, was last seen late on March 31 at his house in South Windsor.

"We haven't been able to find Brendan and in an unusual type of appeal we're actually releasing the CCTV images," Detective Inspector Russell Oxford said.

The newly released footage shows Mr Vollmost being chased into the backyard of his house in South Windsor by four men.

Police allege he was bashed there, before being abducted and driven away in a car.

Police say 23-year-old Brendan Vollmost was abducted from his home in South Windsor on March 31 2015 in a white hatchback. ( Supplied: NSW Police )

"What you'll find with the images is they're very graphic, they're confronting, and above all they're very distressing and it depicts the last moments in Brendan Vollmost's life," Detective Inspector Oxford said.

Earlier in the night, police allege Mr Vollmost had been involved in a car pursuit around South Windsor that ended at his home in Cox Street, where he jumped out of the window of a car and was chased into his yard.

"During the night it would appear that he's been followed and pursued by another car and at one stage [we] believe this car has rammed the car that he was in," Detective Inspector Oxford said.

"What we're anxious to find is that people who view the vision might be able to identify these four men who we believe could assist us with our inquiries."

Police believe Mr Vollmost has been murdered due to the graphic nature of the CCTV footage.

"The indicators are that he hasn't used his bank accounts or his social media accounts [or] his phones," Detective Inspector Oxford said.

"[He] hasn't made any contact with the family."

Sorry, this video has expired CCTV from outside home of Brendan Vollmost ( ABC News )

Mr Vollmost's cousin Jodie Ferris on Wednesday made an emotional plea for anyone to come forward with information.

"We just need some answers to find him," she said.

"It has taken its toll, not only on his mum but his younger siblings, who are suffering," she said.

"They don't understand why their brother's not coming home, or where he is, or why somebody would want to take him.

Mr Vollmost was known to police and officers are investigating his links with a group called the Blood Brothers.

"Little is known about this group. We certainly don't think they're some type of major crime network," Detective Inspector Oxford said.

"It's more what we think is just a group of males, a group of friends, that have come together and called themselves Blood Brothers.

Brendan Vollmost was allegedly assaulted at his home in South Windsor before being driven away in a white hatchback. ( Supplied: NSW Police )

"We've received some information that suggests that the four men that we're looking for may have some connection to this group. We believe they're within the western suburbs of Sydney."

Police said they believe the disappearance was connected with drugs.

"Brendan Vollmost is a young man known to police," Detective Inspector Oxford said.

"We are obviously looking at a line of inquiry in relation to drugs."

Police are also looking for a white hatchback with NSW registration BNY 72R shown in the CCTV footage.

"We're renewing our appeal in regards to smash repairers or scrap metal dealers possibly in the western suburbs of Sydney," Detective Inspector Oxford said.

"The car may have been brought to one of these locations."

Police have urged anyone with information in relation to Mr Vollmost's disappearance to call Crime Stoppers on 1800 333 000.