Police believe they have established the identity of the second victim of the M25 coach crash near Heathrow.
He is said to be East Asian and in his mid 20s, but his name will not be released until his next of kin, who live in China, have been informed.
The 40-year-old driver arrested after the National Express coach overturned on Wednesday has been released.
He was held on suspicion of causing death by dangerous driving and was freed on bail.
Ch Insp Gill Wootton, senior investigating officer, said: "Extensive enquiries have been undertaken in the attempt to identify the man who was a passenger on the double-decker National Express coach.
"We now believe we have identified him, however until we have made contact with his next of kin we will not be releasing his name."
The man, and 76-year-old Christina Toner from Dundee, were killed in the accident.
The London-to-Aberdeen coach overturned, at 2345 GMT on Wednesday, on a slip road from the M4 to the M25 in west London.
Christina Toner, from Monifieth, died in the crash
All those on board the coach, 67 passengers and two drivers, were taken to hospital following the crash.
Fourteen people remain in hospital. Among them, two children and a 25-year-old woman were described as being in a critical, but stable, condition.
Earlier it was revealed that 12 double-decker coaches withdrawn from service following the M25 crash have passed safety checks.
Manufacturers Neoplan said the coaches were thoroughly examined and there should be no concerns among passengers regarding their safety.
However National Express has said the buses will not be returned to service until the company has completed its own investigations.