The man was detained in the west coast city of Gothenburg where the kidnapping took place.
Fabian Bengtsson was reported missing on January 18th and released unharmed in a Gothenburg on February 4th.
Another man was arrested by police in Vienna earlier this week, also suspected of being involved in the kidnapping.
However, the Swedish daily Svenska Dagbladet reports that the Austrian police have since said the man is an impostor who played no part in the kidnapping, but tried to press the Bengtsson family for money by claiming that he was involved.
Gothenburg police say the man in Vienna was still a suspect and are seeking his extradition.