The Austrian man who killed his two siblings and their spouses might have fled to the Czech Republic or Slovakia, criminal police said Friday, reported dpa.
Josef Branis, 66, is suspected of shooting to death his sister and her husband as well as his brother and his brother's wife on Tuesday after a family row.
After committing the crime in the village of Strasshof near Vienna, Branis could have fled by train to the two nearest neighbouring countries, homicide officer Leopold Etz told Deutsche Presse-Agentur dpa.
During police investigations, "we learned that he frequently travelled to Bratislava in Slovakia and to the Czech Republic," he said.
However, the police were merely making an assumption on the suspect's whereabouts and were not drawing any definitive conclusions, Etz said.
Austrian police have issued an international arrest warrant.
Bratislava, the Slovakian capital, is a mere one and a half hour's train ride away from Strasshof. Branis does not own a driver's license.
Branis wiped out his family after his sister evicted him from her apartment in Vienna on Monday. The siblings had been arguing over the rent for the past one and a half years.