New Zealand veterinarian Daniel Hajdu had been shooting in western NSW two weeks before he hitched a ride with Mr Eastman on the south coast on January 15, 1989.

Mr Hajdu told the ACT Supreme Court on Tuesday he had put his backpack in the boot of Mr Eastman’s blue Mazda sedan for the hour journey to Batemans Bay, where he had been dropped off at the turn off to Canberra.

Mr Eastman is accused of shooting Mr Winchester twice in the head at close range as the Australian Federal Police assistant commissioner parked in the driveway next to his Canberra home about 9.15pm on January 10, 1989.

David Harold Eastman, 72, has pleaded not guilty and is on trial for the murder in the ACT Supreme Court.

The court has previously heard that police forensic tests found gunshot particles in the boot of Mr Eastman's car.

The particles were small, green, translucent and flattened balls that were partially burnt.

Another particle, smaller and darker than the others, had been found in material collected from the the driver's side seat.

Acting superintendent in the AFP’s forensics division, Peter Nelipa, last month said the particles found in Mr Eastman's car boot had been consistent to those found on the driveway next to Mr Winchester's Ford Falcon.

However, jurors heard it had not been possible to determine when the particles had been deposited in the boot and there had been 36 types of ammunition produced in Australia that would produce particles of a similar nature at the time of Mr Winchester's assassination.

On Tuesday, the court heard Mr Hajdu had completed two months locum work in Victoria before going on a five-day shooting trip to a western NSW property over the New Year period in 1988-89.

He said the hunting party took about eight firearms, including a number of .22 rifles.

He primarily used a .303 rifle during the trip, however, used a .22 to shoot rabbits on one occasion.

Mr Hajdu said he had carried his belongings in a large backpack and smaller rucksack for the trip, which he kept in his room in the shearer's quarters at the property.

He told the court he had cleaned the firearm using a cleaning kit, and stored the weapon and ammunition, in the same room.

He admitted his backpacks may have come into contact with a rifle, ammunition, and cleaning kit during the stay.

Mr Hajdu was dropped at Hay after the shooting trip on January 2, and hitchhiked his way back to Sydney over the coming weeks, via Darlington Point, Narrandera, Canberra, Narooma, and Gerringong.

He said he had washed his clothes while in Narrandera

On January 15, he accepted a lift from a man named "David", who had spent the previous night in Narooma, stowing the large backpack in the Mazda's boot.

Police surveillance of Mr Eastman had already started, with AFP officer Bruce Waugh tailing him to the south coast, where he took pictures of the defendant at the Narooma shops on January 14.

Mr Waugh, from the witness stand, confirmed he had seen Mr Eastman and Mr Hajdu remove the backpack from the car boot on January 15 before the defendant drove off.

The trial before Acting Justice Murray Kellam continues.