A 44-year-old man has been arrested in connection with the murder of 87-year-old Thomas O'Halloran, an Irish emigrant who was stabbed to death, in West London, on Tuesday. 

Thomas O'Halloran, who was originally from Ennistymon, in County Clare, was riding his mobility scooter in Greenford at the time of the attack and was reportedly on his way back from a Tesco supermarket, where he had been busking with his accordion to raise money for the victims of the Russian invasion of Ukraine.

Metropolitan Police arrested a man with an address in Southall, West London, in the early hours of Thursday morning. 

Detective Inspector Jim Eastwood, who is leading the investigation, thanked the public for their support in identifying the suspect. 

"I would like to thank the public for their overwhelming support following this horrific incident. As a result of the release of a CCTV image yesterday, an arrest has been made and this investigation is progressing at pace," Eastwood said in a statement. 

"Mr. O’Halloran’s family have been updated with this development and continue to be supported by specially trained officers." 

Metropolitan Police had released CCTV images of a man armed with a knife fleeing the scene in the hope of identifying the suspect. 

Police said they responded to reports of a man with stab wounds in Greenford just after 4 pm on Tuesday. They believe O'Halloran was stabbed only a short while earlier, but he managed to travel 75 yards or so in his mobility scooter to flag down a member of the public for help. However, he was pronounced dead at the scene despite the best efforts of the emergency services. 

O'Halloran's 20-year-old grandson, Joey, told the Daily Mail that the family is still in "complete shock" over the attack. 

"The family are still trying to take in what has happened. It is a complete shock. My father called me this morning. He was very upset and didn’t talk much. I just don’t understand why someone would do this to a defenseless old man," he told the Mail. 

Mayor of London Sadiq Khan, who is under pressure due to the rise in violent killings in the city, said he was "devastated" by the killing. O'Halloran was the 67th person to be murdered in London this year and the sixth in four days. 

Meanwhile, a security guard at the Tesco supermarket where O'Halloran had been busking said the suspect had been removed from the store on several occasions on suspicion of shoplifting.

O'Halloran was carrying a charity box with a Ukrainian flag at the front of his mobility scooter at the time of the attack, video footage revealed. 

His friends said that he regularly busked to raise funds for victims of the war, raising around £10 per session. 

A security guard told the Sunday Times that O'Halloran would often "bring a smile to people's faces" before going to Greenford Tube Station to continue to play music. 

Frasley Coutinho, who went to O'Halloran's aid after the attack, described him as a "jolly and peaceful" character, while others remembered how he would honk the horn on his scooter for the amusement of young children. 

Marsha Hill, who lived opposite O'Halloran for more than a decade, said there was "no reason on earth" why someone would attack him. 

"There is no reason on this earth why anyone would see fit to do that to him. It’s just really sad. He wouldn’t hurt a fly. What could he be doing to annoy someone enough to carry out something like that?"