NORTHERN Territory police conducted formal searches for the remains of backpacker Peter Falconio as recently as two months ago, a court was told today.

Territory Response Section sergeant Glenn McPhee said he was involved in a search for the 28-year-old's body at the end of August and early September this year.

He was giving evidence at the trial of Bradley John Murdoch, who has pleaded not guilty to murdering Mr Falconio beside the Outback Stuart Highway in July, 2001.

Murdoch, 47, a mechanic from Broome, Western Australia, has also pleaded not guilty to assaulting Mr Falconio's girlfriend, Joanne Lees, and depriving her of liberty.

The couple were ambushed on the remote highway as they travelled across Australia in a camper van.

Miss Lees, formerly of Almondbury, managed to escape from her attacker and hide in the bush for several hours before being rescued.

Sgt McPhee said police launched a massive search for Mr Falconio the day after he disappeared, about six miles north of Barrow Creek.

Sgt McPhee said: "There was still the possibility that he was alive and so that was our main concern."

During one search officers found a lip balm lid under a tree, where Ms Lees may have hidden from her attacker. Police handed the area over to crime scene officers to gather forensic evidence.

Sgt McPheee added: "I indicated to them that I kept the site as pristine as possible, because it may prove to be significant to the investigation."

But the court has previously heard that the crime scene officers didn't further search the area under the tree, because they thought the TRS were going to.

It was not until three months later that a police group found the lip balm tube and some duct tape, allegedly used to restrain Ms Lees, the court has previously heard.

Further searches on foot, motorcycles and in a helicopter over hundreds of square miles found nothing significant related to the incident, said Sgt McPhee.

The court heard police had been consistently searching along the Stuart Highway for the past four years. Sgt McPhee said he found an indentation under a bush that was consistent with someone sitting for a length of time.

The court has also heard that early searches of the area where Mr Falconio was last seen found three footprints. A police officer said they were on sandy ground and appeared to have broken some vegetation.

He said the footprints were consistent with the sole of a sandal and were found on the side of the road near a bloodstain belonging to Mr Falconio.

The court was told there was no gunshot residue found on the steering wheel of the Kombi van belonging to Mr Falconio.

A gunshot expert told the court a modern 0.22 calibre gun contained a propellant that was different to gunpowder.

He said it was possible the propellant might not smell if fired in a windy area.

Key witness Miss Lees had previously told the court she did not feel any heat from a gun that was allegedly held to her head.

The trial continues.