A British man found dead on a Thai beach had recently spent time in Australia as part of a mining scholarship.
David Miller, 24, and Hannah Witheridge, 23, were found dead on a Koh Tao island beach on Monday.
The pair were bludgeoned to death and a bloodied hoe was discovered 35 metres from the crime scene.
Thai police questioned three Myanmar migrants over the murders on Tuesday but they were later released, News.com reported.
Investigators have also cleared a number of British tourists who had been travelling with the pair.
Police say Miller and Witheridge had been partying at a bar in the hours leading up to their deaths.
CCTV images of the pair have been released showing them walking hand-in-hand towards the beach.
Miller’s family released a statement saying the young man left the UK on July 16 to undertake a six-week work placement with an unnamed mining company in Australia.
“David was an artist by temperament, so talented. He had a creative eye that he carried with him through life and in his degree,” his family said.
“He was hardworking, bright and conscientious, with everything to look forward to.
“David was very giving to his family and friends and we all adored him. He will be sorely, sorely missed.”
Miller finished studying civil and structural engineering at Leeds University in June.
He had planned on travelling around south-east Asia before returning to the UK to complete a masters degree.
Thai coup leader and prime minister General Prauth Chen-ocha said authorities were wokring “swiftly” to find the killers.