The alleged captor of British model Chloe Ayling held her because he needed to raise money for cancer treatment, Italian police documents have revealed.
In his police testimony, Lukasz Herba said he got involved with the group behind the alleged kidnap near Milan because he had leukaemia.
Ms Ayling's lawyer Francesco Pesce has said the 20-year-old was told she would be sold in the Middle East "for sex".
Ms Ayling was allegedly held by a group called Black Death for five days.
She came home on Sunday, after talking to police investigators, 26 days after she flew to Milan for a photo shoot.
Italian police say she was attacked by two men, drugged with ketamine and abducted, apparently to be sold in an online auction.
It is alleged the kidnappers attempted to sell her online for £230,000 and demanded her agent paid a ransom fee.
Mr Pesce said Ms Ayling, from Coulsdon, south London, had gone shopping with her captor because she had been threatened with death.
"She was told that people were there watching her and were ready to kill her if she tried anything," he said.
"So she thought that the best idea was to go along with it and be nice to her captor, because he told her he wanted to release her somehow and some time."
Mr Herba, a Polish national who lives in Oldbury, in the West Midlands, told police he had a change of heart once he met Ms Ayling, according to documents seen by the BBC.
He told investigators he drove her to the British consulate in Milan and released her before the sale went ahead.
Ms Ayling's police testimony says she had met him before - when he was her contact for an earlier photo shoot in Paris - where he introduced himself as Andre.
He cancelled the shoot saying his camera had broken, and came to Paris airport to pay her taxi fare.
She described being abducted in Milan and taken to a hideout by three or four men, but was watched over only by Herba, who slept beside her each night, as she was tied to furniture.
Italian police said she was transported in a car to a house in Borgial, north-west of Turin, where she was handcuffed to a wooden chest of drawers in a bedroom for six days.
Speaking on Sunday, Ms Ayling said she feared for her life throughout the "terrifying experience".
"I'm incredibly grateful to the Italian and UK authorities for all they have done to secure my safe release."
Speaking to the BBC's Victoria Derbyshire programme on Tuesday, Ms Ayling's friend Carla Berlucci, who also runs a model agency, said girls in the industry had to take care.
"Safety is always first, safety is number one," she said.
She described her friend, who she has known since Chloe was 15, as a "good girl, a little bit naive".
Investigations into the case are being carried out by authorities in Italy, Poland and the UK.
Italian officers have arrested Mr Herba on kidnapping charges.
The UK's National Crime Agency said it had been working with the East Midlands Special Operations Unit (EMSOU) and the Italian authorities.
A spokesman said: "A house in the Oldbury area linked to Lukasz Pawel Herba was searched on 18 July by EMSOU officers with assistance from West Midlands Police.
"Computer equipment seized is being forensically examined."