Police said they asked convenience stores and petrol stations to give them footage from closed-circuit cameras to try to identity the pickup used by the attackers as they drove around Pattaya before going out of the city and raping the victims at a reservoir.
Police expect results of tests on the victims to find DNA of the three attackers will be concluded this week.
A source said police had interrogated a garage owner after a person called him and proposed to sell a pickup, as its appearance was similar to one used by the attackers. The source said the person wanted to cut the car apart before selling it to him, but the owner insisted he wanted to buy the vehicle intact, not in parts.