Four arrests have been made after a group of masked men entered a vehicle and stole phones, a watch worth about £450,000 and cryptocurrency valued at about £1.1m.
Two men and three women were travelling in the car in Oxford on the afternoon of 4 November when the men clad in face coverings got inside.
They forced one of the victims to transfer the cryptocurrency out of their account and after 30 minutes left the vehicle in the Five Mile Drive area of the city.
Thames Valley Police said a "complex" investigation followed, with officers conducting warrants and arresting four men on suspicion of offences including robbery and kidnap.
Det Sgt Stuart McMaster said "Thames Valley Police has been conducting a thorough investigation into the offences.
