Detectives were waiting to question one of Scotland Yard's most wanted men today, following his arrest in Bangladesh.
Officers have been hunting Ayab Khan, 27, since a double murder in east London in 2003.
Amarjit Singh, 52, and his nephew Rajinder Singh, 35, were shot dead near the hotel they owned in Forest Gate.
Police are now seeking his formal extradition to Britain following the arrest in Dhakar.
Khan, originally from Chigwell, Essex, was detained as he was on his way to an airport, it was believed.
A Met police spokesman said: "A man believed to be Ayab Khan was arrested on Thursday August 5 in Dhaka by Bangladeshi authorities.
"The arrest was made on behalf of the Metropolitan Police Service. We will now seek the man's formal extradition to the UK."
The Met had offered a reward of £10,000 for information leading to Khan's arrest and conviction. In 2004 he was placed on Scotland Yard's Most Wanted list.
The uncle and his nephew - both businessmen - were shot with an Uzi-style machine gun following an argument, it was reported at the time.
Khan arrived in Bangladesh last week to visit a friend in north-eastern Sylhet district, it was reported locally.
At the time of the killings, the police said the pair may have been shot dead following a row about parking.
Speaking in 2003, Detective Superintendent Maureen Boyle, the officer leading the investigation, said: "Shortly before our victims were killed in Atherton Mews, there were two vehicles blocked by them in that Mews, a blue or green Honda Civic Hatchback and a dark blue Volkswagen Golf.
"These two vehicles had been beeping horns, trying to attract attention because they were blocked in. Amarjit Singh eventually came out and moved the vehicles. The Honda drove off. Before the Volkswagen drove off, there was a heated argument between Rajinder Singh and the driver of that blue Volkswagen."