A Polish man confessed to murdering an Austrian woman and her husband one month after killing another person in Sweden.
Dariusz Pawel Kotwica, 29, admitted to the killings, and authorities believe that he might have struck in Britain as well, reports Daily Mail.
Experts said Kotwica could be the first serial killer to use Europe’s open borders as a means to evade police and target his victims easily over the course of several years, according to Metro.
The man reportedly wrote bizarre phrases on the Austrian woman’s body after killing her, the Daily Mail reports. Authorities said he spoke of the “joy” he felt from taking his victims’ lives, saying that voices in his head told him to carry out the murders.
Kotwica reportedly lived in the U.K. for several years, leading police to believe he carried out “serious crimes” during that time. He was first sought by police after the husband and wife in Austria were stabbed to death on May 21. Their bodies were discovered by relatives.
Kotwica is currently awaiting trial in Austria.