DNA samples taken from a garden hoe believed to have been used in the murder of British tourists Hannah Witheridge and David Miller in Thailand last year does not belong to the two men who are standing trial, a top Thai forensic expert has told the court.

The revelation is the latest in a string of inconsistencies in the police investigation into the brutal killings. During a three-month trial, police have been accused of improperly collecting evidence at the crime scene, intimidation and abuse of witnesses.

Thai police deny any wrongdoing.

The head of the Thai forensics institute, Porntip Rojanasunand, told judges on the island of Koh Samui that her team had identified DNA on a garden hoe, found bloodied near the deceased on a beach on Koh Tao island in September last year. The samples belonged to two males but there was no match with the defendants, she said.



The chief judge had allowed Porntip to retest the hoe at the request of defence lawyers, who are working pro-bono to support the 22-year-old bar workers, Zaw Lin and Wai Phyo, who are from Myanmar.

Wai Phyo (L) and Zaw Lin (R) are on trial for the murder of two British tourists. Photograph: Sitthipong Chareonjai/EPA

In Thailand, filming, recording or taking notes in courts is forbidden. The Guardian spoke to the defence team and an observer in the court to confirm Porntip’s statement.



Porntip has become something of a celebrity in Thailand after working on several high-profile and politicised cases. She has a wax statue at Madame Tussauds in Bangkok.

But she has also attracted controversy, notably for supporting British-made GT200 “bomb detectors” that were proved not to work.

The murders on a idyllic beach shocked the UK and Thailand due to their brutality. Witheridge, 23, from Norfolk, and David Miller, 24, from Jersey, were found on Sairee beach with severe head wounds. Police say sperm collected from the crime scene implicates the two defendants, but have not provided samples for retesting.

Witnesses, including police, doctors and people living on the island, are due to testify until 25 September. A verdict is expected a month after the end of the trial.

Human rights groups including Amnesty International have become involved in the trial, noting that migrant workers from Myanmar, of whom there are about 2.5 million in Thailand, have previously been wrongly accused of crimes by Thai police.