It's thought that Dariusz Pawel K, 29, may have killed victims in six European countries over several years. He has been dubbed the ‘Euro Ripper' by the British press.
He was arrested in Germany earlier this year and extradited to Austria where he confessed to the torture and murder of a 74-year-old woman and her husband in Vienna in May.
A drifter and career criminal, he told Austrian detectives he had also killed a Swedish pensioner the previous month.
K. is now in custody in Vienna, awaiting trial. He told detectives that an “inner voice” had told him to murder the elderly Austrian couple, whose bodies were discovered by their son. They had been battered and stabbed in a violent attack, and K. had daubed the word TANTAL on the woman's naked body in paint.
In the latest development, an official report commissioned by the UK Home Office claims that K. lived in the UK for “several years” and detectives fear he committed “serious crimes” there.
There have also been reports of possible murders in the Czech Republic and the Netherlands.
“We are quite sure he has committed many more crimes and perhaps additional homicides,” Austrian police officers said in a report.
A spokesman for the state prosecutor said that if K. is found to have committed serious crimes in Britain he will not be extradited until he has served his sentence in Austria.