Sickening Ring doorbell audio caught the moment a drug dealer boasted about fatally stabbing a university student five minutes after doing so. 

Dino Donaldson murdered 21-year-old accounting student and black belt karate ace Anojan Gnaneswaran at Strawberry Hill station in Twickenham after a drug deal turned violent.

While he was walking away, he accidentally activated a Ring doorbell near the scene and was heard boasting about the murder to one of his associates. 

'I stabbed a man in his back bro, I stabbed him through the back bruv - I stabbed him fully,' he says on the recording. 'I watched it and I felt it go in him. Yeah?' 

Donaldson then boarded the N87 night bus, where an on-board camera caught him laughing and smiling. He can also be seen reaching out to shake someone's hand before they exchange a fist-bump. 

Donaldson, from Ealing, was arrested by detectives from the British Transport Police's Major, Serious and Organised Crime (MSOC) team. 

Jurors found him guilty of murder on Wednesday. 

Earlier, the Old Bailey heard how two groups of young men arranged a deal of £50 for 10 MDMA tablets to be exchanged at Strawberry Hill on the evening of January 8, 2024. 

Donaldson and three others arrived just after 10pm, followed by Mr Gnaneswaran around an hour later.

There was a disagreement between the two parties and Mr Gnaneswaran called his brother, who came to the station with two others.

The argument continued on the platform before Donaldson pulled a long knife out of his waistband.

He chased the group and caught up with Mr Gnaneswaran on the railway tracks where he stabbed him in the chest, abdomen and thigh.

The victim's brother phoned 999 and began CPR before paramedics arrived to take over. But the youngster died at the scene. 

BTP detectives traced Donaldson's movements after the attack using CCTV as he fled from Twickenham to Kingston Upon Thames.

A search team found the knife and a black glove in a tree at the murder scene. Forensic examination found DNA belonging to Donaldson and Anojan on both items.

Officers raided Donaldson's home on January 11, 2024 and found him hiding in a cupboard. 

BTP Detective Chief Inspector Paul Attwell said: 'What started as an argument over a drug deal ended in a young man's life being cut short by a remorseless thug.

'Donaldson showed his true colours as a coward by arming himself with a knife that night. His cowardice has continued by never accepting responsibility and admitting his crime – thankfully the jury saw through his lies.

'He will live the rest of his life knowing he has taken someone else's, and next month he will learn that he has a long time behind bars ahead to mull over his actions.

'While no verdict can ever compensate for the loss of Anojan, I hope today's outcome provides his family with some sense of closure. 

'Thanks to our extensive investigation, justice has now been served to the man responsible for killing their loved one.'

Mr Gnaneswaran's family have paid tribute to their 'much-loved son and brother'. He was a karate ace who competed in the World and European championships.

They said: 'Anojan was in his third year at university studying accounting and finance, and he was so excited for his future.

'He excelled at all sports and had achieved first-dan black belt in karate – he competed in the World and European championships in karate, and we will all miss him so much.'

Donaldson will be sentenced on June 19.