The four men who have admitted stabbing two Newcastle University medical students to death in Borneo were high on Crystal Meth, the police report states.
The four men attacked Neil Dalton and Aidan Brunger following a row in bar that began after the British students were being too noisy, it is reported.
Deputy police chief Chai Khin Chung said four male suspects, aged between 19 and 30, have confessed to the killings. According to local law, they will now face the death penalty.
He said the two Newcastle University students had been drinking and began arguing loudly in a bar when the suspects confronted them and told them to be quiet.
"Then one of the British students slapped one of the locals, turned over a table, and walked out," he said.
Dalton and Brunger were working on the Malaysian part of the island during a six-week placement alongside five other students from their university, in a hospital in Kuching.
The other students are receiving counselling from staff at the hospital over the tragedy and a member of staff from Newcastle University is said to be flying out to the region "as soon as possible" to co-ordinate their return to the UK.
Dalton and Brunger, 23 and 22, were followed in a car and then attacked by local men as they made their way back from a night out at a bar in the city of Kuching, in the early hours of the morning. They were reportedly found with stab wounds to the chest and back at 4.15am local time on Tuesday.
The attack happened in the Jalan Padungan area of Kuching in Sarawak state, in the west of the Malaysia part of Borneo.
Professor Tony Stevenson, acting vice chancellor of Newcastle University, said: "We are all very shocked and extremely saddened by their deaths and our thoughts are with their families and friends at this very difficult time."
The deputy commissioner said they had now finished their investigation, as the men confessed, and they would now be passing on their evidence for prosecution.
"We have finished our investigation, the crime has been solved," he said.
"The suspects have been apprehended and they have admitted the crime. We have recovered the weapons from the crime.
"We are waiting for the corpses in the hospital mortuary to have the post-mortem carried out. We have all the major evidence in our hands which we will send to the prosecution."