Joseph Kappen, who was posthumously linked by DNA evidence to three murders in 1973, is being investigated about a nine-year old girl who went missing the same year.
South Wales Police confirmed last week that DNA samples taken from the remains of Kappen, a suspect in the murder of friends Pauline Floyd and Geraldine Hughes in September 1973 and Sandra Newton the previous July, matched samples taken from the victims, all aged 16. Humberside police are reopening the case of Christine Markham, who disappeared from her home in Scunthorpe, that May. A police spokeswoman said that without a crime scene there was no DNA evidence, and there were "differences" between the Wales murders and the disappearance of Christine.
Kappen is thought to have lodged in the area that summer and worked as a lorry driver in Scunthorpe. He died of cancer in 1990 when he was 49.