‘My son stepped in to help out a 
girl in trouble’

Ian Miller said it was in his 24-year-old son David’s character to help, and claimed that was probably the circumstance when the Leeds University graduate and Hannah Witheridge were murdered in Koh Tao a week ago.

He said: “It has become clearer and clearer that it is quite likely David was stepping in to help a girl who was in trouble.

“That would be absolutely in his character.”

Thai police were yesterday reported to be expanding DNA testing on the island and say they want to check every male there amid suggestions officials have been stung by criticism of their performance, with around 150 officers deployed in the operation.

The body of Miss Witheridge, 23, has been brought back to the UK.

While Thai media reports suggest there are now two main suspects in the investigation Police Colonel Kissana Phathanacharoen said: “There are more than two suspects.

“It is too early to say how many suspects we are looking at.”

A spokesman for the Royal Thai Police said that the force was also looking into claims that the pair had a row with a Thai man in a bar before they were killed.

Mr Miller said his family had not been given much information from Thai police on the progress of the investigation.

Mr Phathanacharoen said he would be happy to speak to Mr Miller and pass on any information they had.

Post-mortem examinations revealed that Ms Witheridge, from Great Yarmouth, Norfolk, died from head wounds while Mr Miller, from Jersey, was killed by severe blows to the head and drowning.

A bloodstained garden hoe, believed to be the murder weapon, was found nearby.

Thai police are offering a cash reward worth about £4,000 for information that leads to the arrest of the suspects. Residents on the island have also raised further cash.

Police have said they were looking for more than one suspect following unconfirmed reports that the DNA of two Asian men had been found on Ms Witheridge’s body.

A group of Burmese migrants who were interviewed by police after bloodstains were found on their clothes have also been eliminated from inquiries.

No matches were found between them and DNA found on Ms Witheridge and a cigarette butt at the scene.

As many as half a million travellers visit the island every year although it has a resident population of barely 2,000.