British couple-murder accused's DNA not on weapon

DNA samples taken from a garden hoe believed to have been used in the murder of a British couple in southern Thailand last year do not belong to the two men who are standing trial, a top forensic expert said.

Two 22-year-old Myanmar nationals, Zaw Lin and Wai Phyo, were arrested two weeks after Hannah Witheridge, 23 and David Miller, 24, were found brutally murdered on on Sairee beach in Koh Tao island, on September 15, 2014.

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, The Guardian reported.

However, the samples did belong to two males but there was no match with the defendants, she said.

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 have denied any wrongdoing.

Witnesses, including police, doctors and people living on the island, are due to testify until September 25.

A verdict is expected a month after the end of the trial.