A Polish man, who lives in Britain, was arrested on July 18 on suspicion of kidnap and extortion, state police said.
A British model was drugged and abducted for a week in Italy last month by a British-based Pole who allegedly tried to auction her off as a sex slave on the dark web, Italian police said Saturday.
Police say it is unclear whether he had really abducted the victims or invented them for the auction.
Authorities said the kidnappers were going to release her "because she had a 2-year-old child" and their "rules exclude kidnapping mothers".
Police said she was injected with an anaesthetic when she arrived at a Milan apartment, put inside a suitcase and taken in the boot of a auto to a village in the Piedmont region.
The kidnapper used an encrypted account and then asked the model's agent for $300,000 to stop her from being sold in auction.
They said she was handcuffed to a dresser until she was released near the British consulate on 17 July - with the kidnapping suspect arrested the day after.
The woman was then kept handcuffed to a wooden chest of drawers in a bedroom for six days until she was released.
As reported by the Daily Beast, on receiving the ransom demand from Herba, the United Kingdom modeling agency contacted the police, whereupon he negotiated with them to return the model for a fee of $60,000, saying he would kill her if they did not comply.
Italian media reports that Herba has links to the "Black Death" criminal organisation that works on the dark web.
A spokesperson for the Foreign Office confirmed they are "providing consular support to a British woman in Italy and are in touch with local authorities".
It was not immediately clear why the suspect took the model to the consulate.
While holding her hostage, the man demanded around £45,100 (€50,000) from her if she wished to be freed.