Bangkok , Thailand ( CNN ) -- Thai police are still searching for suspects in the killings of two British tourists on an idyllic resort island after DNA tests on more than a dozen men found no matches with evidence from the female victim 's body . Provincial police chief Kiatthipong Khaosumarng said that experts carried out the tests on DNA samples from 11 migrants working on the island and two British brothers , one of whom had shared a room with the male victim . No one has been arrested yet over the killings on the island of Koh Tao , nor has anyone been officially named a suspect . Police had previously asked the two British brothers , Christopher and James Ware , not to leave Thailand , saying they were `` under watch . '' Kiatthipong declined to comment on reports that the two brothers have now been allowed to leave Thailand . Police are now trying to find other people who were caught on surveillance video the night the two tourists -- Hannah Witheridge , 23 and David Miller , 24 -- were killed , he said . An autopsy revealed both victims had been hit by a hard object , according to Maj. Gen. Pornchai Suteerakhun , the head of the Police Hospital 's Institute of Forensic Medicine . Miller was hit and had scratches on his back , in addition to having water in his lungs consistent with drowning , an autopsy showed . Witheridge was hit several times on her head and face and her body had evidence of sexual intercourse , according to her autopsy . Pornchai did n't confirm or deny that authorities believe Witheridge was raped . Kiatthipong said that two sets of DNA have been found on Witheridge 's body , indicating at least two culprits in her death . Neither set matches that of Miller , he said . Family : ' A beautiful , intelligent , loving young woman ' Police previously said they had ruled out robbery as a motive . Miller and Witheridge were last seen with friends at a bar in the early hours of Monday before leaving together , according to Kiatthipong . Police have released a grainy image from video outside that bar , adding that they wanted to interview a person -- who they described as an Asian man -- seen in it . The victims were discovered partially undressed with severe injuries to their heads , and a hoe with blood on it was found near the bodies , police said . The deaths have shaken residents on popular holiday island , which takes up only 21 square kilometers ( 8 square miles ) amid bright blue waters in the Gulf of Thailand . Authorities said it was the first homicide case on the island -- known for its diving locations , white-sand beaches and vibrant nightlife -- in at least eight years . The confusion and heartache there , though , pales compared to that felt now half a world away in Briton , where two families are coming to grips with their loved ones ' deaths . In a statement issued by the British Embassy in Bangkok , Witheridge 's family said she was `` a beautiful , intelligent , loving young woman who poured joy into the lives of all who knew her '' and they were `` utterly devastated and shocked by what has happened . '' Miller 's family described David Miller as `` an artist by temperament , so talented . `` He had a creative eye that he carried with him through life and in his degree . He was hard-working , bright and conscientious , with everything to look forward to . '' CNN 's Greg Botelho , Katie Hunt and Jethro Mullen contributed to this report .
NEW YORK (AP) — DNA was taken from two British brothers and 11 other men . Autopsy : Slain woman had signs of sexual intercourse , getting hit in head . The male victim had water in his lungs , was hit by hard object , police say .