The man accused of UK backpacker Peter Falconio's murder took amphetamines to stay awake as he ran drugs across Australia, a court has heard.
Mr Falconio's body has never been found
Bradley Murdoch, 47, also carried a gun, his former drug trade partner James Hepi told the Darwin court.
Mr Murdoch seemed "scattered" on his return from a drugs run in July 2001, having taken amphetamines for up to five days, Mr Hepi said.
Mr Murdoch denies murder and abducting Mr Falconio's girlfriend Joanne Lees.
Mr Hepi, a New Zealander, also told how his ex-drugs partner had shaved off his moustache and cut his hair short to change his appearance after the trip, at the time of Mr Falconio's disappearance.
When Mr Falconio's disappearance was reported in the media, the defendant had said: "It wasn't me", the Northern Territory Supreme Court heard.
Mr Hepi said Mr Murdoch always carried a handgun in his pickup truck as he drove across the country with marijuana hidden in the fuel tank.
He also described for the court how he had discovered Mr Murdoch making handcuffs out of cable ties in his backyard shed before Mr Falconio, 28, disappeared.
The court has already heard Ms Lees describe how she and Mr Falconio were driving across the Outback near Alice Springs when they were flagged down by Mr Murdoch.
He is then alleged to have shot the backpacker and bundled his girlfriend into the back of his van, binding her in make-shift handcuffs.
But Ms Lees, 32, of Brighton, says she later escaped and hid in the undergrowth for five hours until her abductor gave up searching for her and left.
The court also heard Mr Hepi say his former drugs partner had told him that a drainage trench on an Outback road was a "fairly good place to put a body".
Mr Falconio's body has never been found.
Under cross-examination, Mr Hepi denied he had made up the story to get a lighter sentence when he was arrested for drugs in Broome in 2002.
He told the court he had fallen out with Mr Murdoch over a drugs deal.
The trial continues.