Thai police are offering a reward of more than £13,000 (700,000 baht) in an effort to catch the killers of two British tourists, as a group of footballers were questioned by officers investigating the murders.
The bodies of David Miller and Hannah Witheridge were found on a beach on the island of Koh Tao on September 15.
A blood-stained garden hoe, which is thought to be the murder weapon, was discovered nearby.
It is believed at least three men were involved in the attack.
A group of Thai footballers are the latest people to be questioned by detectives, amid fears the hunt for those responsible for the murders has stalled.
A police officer searches for clues near where the bodies were found A spokesman for the Royal Thai Police confirmed DNA samples have been taken from "more than eight" footballers who reportedly threw a late-night party at the nightclub where the victims were on the night they died.
Officers are awaiting the results.
Police colonel Kissana Phathanacharoen said a reward of 700,000 baht - which is roughly £13,300 - was now being offered for information.
"We're trying to narrow our inquiries and collect more evidence," he said. "We're encouraging the public who many have information to come forward.
"We're checking DNA but this is not the only thing we are looking at to prosecute the suspects."
Hannah Witheridge seen on CCTV in the hours before her death Post-mortem examinations revealed that Ms Witheridge, 23, from Great Yarmouth, Norfolk, died from head wounds, while Mr Miller, 24, from Jersey, suffered severe blows to the head and subsequently drowned.
Ian Miller, David's father, earlier this week said he thought his son might have intervened to help Hannah during an argument.
"It has become clearer and clearer that it is quite likely David was stepping in to help a girl who was in trouble," he told the Daily Mail.
Around 150 police have been sent to the island to try to find the killers.
Koh Tao is popular with tourists In light of the killings, Deputy Prime Minister Prawit Wongsuwan has instructed police forces to fit more security cameras in tourist destinations, and wants more streetlights in these areas to deter criminals, the Phuket Gazette reported.
A group of Burmese migrants interviewed by officers after bloodstains were found on their clothing were eliminated from inquiries last week.
No matches were found between them and DNA found on Ms Witheridge and a cigarette butt at the scene.
Police have previously said they were looking for three Westerners who were seen playing a guitar near Sairee beach.

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