Work colleagues who witnessed the shooting of the British businessman Michael Hamilton said the militants tied his body to a car and dragged it through the streets before dumping it near a bridge.
Mr Hamilton, 62, originally from Kilmarnock, south-west Scotland, worked as a senior manager in the project and trade finance department of the Arab Petroleum Investments Corp (Apicorp).
His wife, Penelope, is now being cared for by the head of the British Trade Office in Khobar. The couple's children - Charles who works as a lawyer in London and Juliet who studies medicine in Australia - may be travelling to join her.
Mahdi al-Mahdi, an Apicorp spokesman who has known Mr Hamilton for the past 16 years, said: "It is very, very sad - especially that way he was being targeted. Everybody here is absolutely devastated by his sudden death. He was a very nice, pleasant man and extremely hard working.
"I have spoken with his wife and she is absolutely shattered by his death." Mr Hamilton, who has a law diploma from King's College London, joined Apicorp in 1989 after working for four years as a credit officer at the National Bank of Abu Dhabi. He had also worked at the Chase Manhattan bank in London.Reuse content