The double murderer, who has sought asylum in the UK, will be sentenced on Wednesday for killing a man after an argument over a scooter.
Lawangeen Abdulrahimzai on Monday pleaded guilty to the murder of 21-year-old Thomas Roberts in Bournemouth, Dorset, last year.
After the verdict was announced at Salisbury Royal Court, prosecutor Nic Lobbenberg revealed that Abdulrahimzai had previously been convicted of murdering two people in Serbia.
He was found guilty of two murders and a related firearms charge in 2020 after a trial in absentia for having already fled Serbia.
He was sentenced to 20 years in prison for crimes that took place between 31 July and 1 August 2018.
Abdulrahimzai fled his hometown of Afghanistan after he said his family had been killed and tortured by the Taliban.
Mr Roberts was acting as a “peacemaker” after his friend James Medway got into an argument with Abdulrahimzai in the early hours of 12 March 2022.
Mr. Medway wanted to buy an e-scooter that Abdulrahimzai had requested for him and leaned against the window of the Subway sandwich shop on Old Christchurch Road.
In the shootout, which lasted just 24 seconds, Mr. Roberts slapped Abdulrahimzai in the face.
Abdulrahimzai later uncovered the knife he had hidden between the two pants he was wearing and stabbed Mr. Roberts twice before fleeing into the nearby woodland.
He buried the knife in the forest before burning the pants, jacket and Afghan flag he wore as a scarf.
However, he dropped his cell phone while fleeing and was traced to his home address.
Abdulrahimzai shared photos of him posing with a knife about 10 inches long on social media and video sharing application TikTok in the months before the incident.
She was seen carrying a knife by her step-parent, who warned her not to, and was also warned by the police and social workers about the dangers of carrying a knife.
Abdulrahimzai told the court he carried a knife and received death threats in Bournemouth because he “feared” for his life as there were people from Afghanistan who wanted to kill him.
The defendant said he shared photos of his knife on TikTok to gain followers from “people who love the knife”.
Abdulrahimzai, who was living in Poole at the time of the crime, arrived in the UK in December 2019 and told authorities he was 16 when he was arrested, but since then the court has ruled that he is now 21.
In his defense, Abdulrahimzai said he had no intention of killing or seriously harming Roberts, “acting on instinct”, “fearing for his life” and felt he had to defend himself.
He will be sentenced in the same courtroom by Judge Paul Dugdale on Wednesday.