The 67-year-old man was named as Gabor P and had a criminal past, according to the Kronen Zeitung.
The gang caught him in the stairway of his home in Floridsdorf, Vienna, injected him with an anaesthetic and then took him to Hungary, the Hungarian news agency MTI reported. They then made him give up the contents of his bank accounts to them.
Gabor P, who has Austrian-Hungarian dual citizenship, was abducted on August 3rd. On August 7th, his sister reported his disappearance to the Austrian authorities, who began investigating.
According to the police report, the victim was forced to sign various documents which the gang then used to gain access to his bank accounts. A woman, wearing a disguise, was the one who made the withdrawals.
A week ago, the gang brought the victim back to Austria, leaving him in an overgrown area by a motorway exit.
According to the police report Austrian policemen found the "distraught" victim near the border crossing of Nickelsdorf.
Hungarian investigators arrested the gang members, reported to be a man and woman from Hungary and a Romanian, last weekend.
Gabor P, a former tax advisor, is said to have been charged in Hungary for defrauding his business partners, and had served time in an Austrian prison.