Gwent police were called to the Sirhowy Arms hotel in Argoed, Blackwood, in the early hours of Thursday morning after reports of a man attacking a woman.
Ms Yemm was reportedly found being attacked by 34-year-old Matthew Williams. She later died as a result of her injuries.
Mr Williams was stunned by a 50,000 volt Taser by police and arrested at the scene but became unresponsive. He was given first aid by officers and paramedics but was pronounced dead at the scene.
Gwent police said they are treating Ms Yemm’s death as murder and are not looking for anyone else.
Her family are being supported by specialist officers.
Facial injuries
Police have refused to comment on the specifics of the incident, but sources have confirmed that Ms Yemm received substantial facial injuries.
At the Argoed hotel where Cerys Yemm was killed, police say speculation around the death has been ‘unhelpful’ pic.twitter.com/fJxd1JBQ6E
As well as the murder investigation, the Independent Police Complaints Commission (IPCC) watchdog has launched its own probe following the man’s death.
A police statement said: “We are co-operating fully with the IPCC, which is independently investigating the death of the man.
“At this time our thoughts are with the families of the deceased following this extremely tragic incident. Our officers who attended the incident yesterday are being fully supported by our force occupational health department.
“The post mortem for Cerys will start today, although may not be complete for some time.”