David and 25-year-old Hannah Witheridge from the UK were found murdered on a beach on the diving resort island on Koh Tao on Monday.
Suspicion first fell on Burmese migrant workers, but coverage this morning suggests it has shifted back to British backpackers. Various reports suggest that two brothers from Jersey were stopped from boarding a flight back to London, and that someone David was travelling with have been interviewed.
More than 70 Thai police are now on the case in Koh Tao, and have been questioning migrant workers and tourists, and visiting hotels, bars and homes.
Police are saying that six Burmese nationals arrested remain in police custody and have undergone DNA testing – they initially said that three arrests had been made on men from Burma.