The DNA found in the female victim's body in the Thailand double murder belonged to two Asian men.
David Miller, 24, and Hannah Witheridge, 23, were beaten to death and their bodies found semi-naked Sep 15 near a beachside bungalow on the island of Koh Tao, the Bangkok Post reported.
Witheridge's skirt was hiked up to her waist and her T-shirt pulled up. She was raped and had a huge injury on her face.
Miller was found naked with an injury to the back of his head.
A bloodstained hoe (a hand tool used for gardening) was found at the scene, police added.
According to police, the test results from the semen found in Witheridge's body indicated the suspects were Mongoloid and not Caucasian.
Earlier, the autopsy on Witheridge found semen from two people but subsequent DNA tests found no matches to any of the seven people detained - six Myanmar labourers and one Briton.
A cigarette butt found near the bodies Friday contained the DNA of Witheridge and another person. It was believed the second person was someone she knew because the cigarette was shared.
DNA on the cigarette matched the semen samples found in Witheridge.
People on the island, from tourists to fishermen and workers, are being investigated, police said.
A senior police official said that Witheridge and Miller have died from severe head injuries.
The couple had arrived on the island Aug 25.
According to witnesses, Miller and Witheridge were seen partying on the beach with a group of about six people the night they were murdered.
Koh Tao, home to white sand beaches and azure waters, draws hordes of foreign backpackers to its "full moon" parties.
