A 53 year old man was arrested in the London area and a 59-year-old in Ayrshire over the death of Ansar Shah in Ayrshire on 4 October 1993
Mr Shah, 36, who ran the Armaan Brasserie Indian restaurant, was stabbed in an Ayr seafront car park.
The operation has been led by Police Scotland’s homicide governance and review team.
A Police Scotland spokesperson said: “Enquiries are ongoing.”
A man was separately arrested in Germany in November last year in connection with the alleged murder.
The 51-year-old was arrested under a European arrest warrant in Frankfurt over Mr Shah’s death.
He was later transferred to Scotland.
Police Scotland, the Crown Office and the UK National Crime Agency were involved in that joint operation.
Europol and French and German authorities also assisted.
Detective Chief Inspector Mark Bell of Police Scotland’s homicide governance review team said at the time: “Police Scotland is committed to pursuing those persons who are allegedly responsible for the gravest of crimes.
“Time and location is no barrier to the efforts and determination of our staff and partners to pursue justice for victims and their loved ones.”