Gwent police identified the victim as 22-year-old Cerys Marie Yemm, who died from her injuries at the scene at the Sirhowy Arms Hotel in Argoed, Blackwood, a town in southern Wales.
Her attacker was identified as Matthew Williams. He also died at the scene.
Police responded to a call that a woman was being attacked and reportedly found Williams committing an act of cannibalism.
"A Taser was discharged and a 34-year-old local man was arrested. Whilst under arrest the man became unresponsive. Officers and paramedics administered first aid, but he was pronounced dead at the scene," Chief Insp. Paul Staniforth in a statement.
Williams was recently released from prison where he was serving time for an attack on a woman. He lured Yemm back to his room before the attack, The Telegraph reported.
Yemm's family is being supported by specialist officers, police said. Police who arrived at the scene were also receiving counselling.
Police are not looking for anyone else in connection with the attack. The case has been referred to the Independent Police Complaints Commission, to investigate Williams' cause of death.