A man has been arrested on suspicion of murdering a 48-year-old man who was stabbed to death on a bus.
Archie Sheppard, from Neasden, north-west London, was subject to a "violent and sustained attack" on the top deck of a Route 189 bus before being discovered by a passenger.
Police and paramedics were called to the bus in Gloucester Place, Marylebone, at 12.10am on Friday but he was pronounced dead at the scene.
On Saturday detectives arrested a 38-year-old man in Mulgrave Road, Fulham, south west London, on suspicion of murder.
He was also detained on suspicion of possession of an offensive weapon after being found with a knife.
Scotland Yard appealed for help in searching for a white male seen with Mr Sheppard shortly before he boarded the bus in Brent Cross, north London, at 11.13pm on Thursday.
The attacker then fled the bus as it reached Gloucester Place and the junction with Montagu Place, heading in the direction of Marble Arch, police said.
Detective Chief Inspector Noel McHugh, said: "Whilst we have made an arrest this evening this is just the beginning for my investigation. We are now appealing to those who knew Archie Sheppard in whatever capacity to come forward.
"It is important that we establish and get a clearer picture as to who Mr Sheppard was and the lifestyle he was leading, in particular anyone who was with him on Thursday, 27 April and anyone who stayed at his home in Neasden.
"I am also making a fresh appeal for information and witnesses to come forward. A number of people have assisted us with our inquiry but there are still a number of witnesses that have yet to come forward and I believe that they could hold vital information that could help with progressing this investigation."
A post-mortem examination was due to take place on Saturday and Mr Sheppard's next of kin have been informed.
Anyone who witnessed the incident or the events leading up to the murder has been asked to contact the incident room on 020 8785 8099 or via Twitter @MetCC.
Information can also be reported anonymously to Crimestoppers on 0800 555 111 or via the crimestoppers-uk.org website.