text: The bodies of David Miller, 24, and Hannah Witheridge, 23, were discovered on a beach in Koh Tao on 15 September.
  Metropolitan Police officers flew out last month to work with Thai police, who are holding two Burmese suspects.
  The UK detectives will now compile a report and "update the families of Hannah and David," a spokesman said.
  "Detectives from the UK who are currently in Thailand reviewing the investigation into the murders of Hannah Witheridge and David Miller have completed their work, as far as possible," the Met Police said in a statement.
  "They will now be returning to the UK to compile their report and to update the families of Hannah and David on their findings.
  "The police team wish to thank the Thai authorities for facilitating the visit."
  Zaw Lin and Win Zaw Htun, both migrant workers from Myanmar, also known as Burma, are alleged to have confessed to the killings.
  Thai police have denied subsequent reports that the pair, both aged 21, have since withdrawn their confessions.
  The two suspects are charged with conspiracy to murder, conspiracy to rape and robbery, and could face the death penalty if found guilty.
  However, the UK Foreign Office last month summoned the Thai charge d'affaires to express concerns about the police investigation.
  The concerns are understood to have been around the verification of DNA samples of the suspects and allegations of their mistreatment.
  The UK police visit came after Thai Prime Minister Gen Prayuth Chan-ocha met Mr Cameron at a summit in Italy and agreed that a delegation of British officers could travel to Thailand.
  He had previously rejected offers of assistance.
  Post-mortem examinations found Mr Miller, from Jersey, died from drowning and a blow to the head, while Miss Witheridge, from Great Yarmouth, died from head wounds.
  Thai police have said DNA found on Ms Witheridge matched samples taken from the suspects.
target: UK police are to return from Thailand after reviewing an investigation into the murders of two British tourists, Scotland Yard has said.