The story of Chloe Ayling's kidnap by a sex slave gang "seems incredible", said her lawyer, but he has stressed that he and investigators believe it is true.

Ms Ayling, a 20-year-old glamour model, says that she was lured to Milan to take part in a photo shoot. But once she got there she was captured, drugged, and taken to an Italian farmhouse where she was held by her captors.

Several days later – apparently because her kidnappers didn't realise she was a mother – she was dropped off at the British consolute in Milan, and she has been there for weeks since. When she was dropped off, the man who had taken her on the journey was arrested as a suspected kidnapper.

Police have gone on to find various references to the "Black Death Group" and its involvement in the kidnapping, including a letter that instructed Ms Ayling to make sure that she gained the group good publicity.

Her lawyer has agreed that the case sounds bizarre. He said investigators initially had "more than understandable doubts" about the model's story.

"It seems incredible," lawyer Francesco Pesce said — "a man kidnaps, together with others, a girl, and after a week, citing particular reasons, accompanies her inside a consulate ... (and) practically hands her over to police."

"This at first was doubted also by investigators — but the story later turned out to be true," he added.

Italian police told the Mail that neither Mr Herba or Ms Ayling had co-operated with the initial stages of questioning. Ms Ayling's manager, Philip Green, told The Independent that Italian police had "detained" Ms Ayling after the kidnapping was reported by confiscating her passport but that it wasn't clear why.

Ms Ayling was little known before the kidnap. Google searches for her name reveal a string of appearances on The Sun's page three, a story about her having been present during a terror attack in Paris, and her participation in a YouTube prank video in which she pretended to be a vlogger's boyfriend.

There was no mention that Ms Ayling had gone missing in the media before last weekend, when she identified herself as the model who Italian police had said had been kidnapped. But police sources said that such a decision may have been made for operational reasons and that any missing person wouldn't necessarily be publicised.

Since Ms Ayling has arrived back in England she has only given a short statement to the press. In that she said that she was being debriefed by British authorities, something that police sources said would tend to happen in cases where there could be intelligence about a broader crime group.

"I've been through a terrifying experience," Ayling said outside her home. "I've feared for my life, second by second, minute by minute, hour by hour."

Police have repeatedly suggested that the suspect, Lukasz Pawel Herba, is a dangerous man. But they have also called him a fantasist and said that he exhibits signs of mythomania.

He is accused of having taken Ms Ayling to sell her as a sex slave to the Middle East, for as much as $300,000. When they would grow tired of her, they would feed her to tigers, Italian newspapers reported him as having said.

As the kidnapping came to an end, Mr Herba attempted to sell the story of a British model being kidnapped by the Russian mafia to the Daily Mirror, reports have claimed. Ms Ayling has said that she had no awareness of that contact, which would presumably have undermined any attempt to traffic her.

The newspaper said that it had received a message that referenced Ms Ayling on 13 July, two days into the kidnap, that was also addressed to The Sun and the agency that represented the model.

"There was nothing in the email to suggest it was from the alleged kidnappers, nor was it an attempt to sell a story about a kidnap," a spokesperson said. "We contacted the modelling agency copied into the email, but our call was not returned. No further emails were received."

It has also emerged that Ms Ayling went shoe shopping with her kidnapper, while the ordeal was still taking place. She told police officers that was because she knew that he was planning to hand her back, and her lawyer said that she had been told that people were watching and would kill her if she attempted to escape.

Police have also questioned why Mr Herba apparently made himself available to be arrested when he handed Ms Ayling over, as it emerged that the pair may have gone for breakfast in Milan after they arrived to find the consulate hadn't yet opened.

It isn't clear whether the Black Death group that he claims to have belonged to actually exists. The image that has become associated with the group – including on flyers found by police – is easily accessible through Google Images, and is the fifth search result for the phrase "Black Death".