This is the doctor accused of drugging a woman with Rohypnol-laced strawberries and keeping her captive in a sound-proof bunker he had built under his rural property in Sweden.

Martin Trenneborg, 38, will face a trial in Stockholm next week charged with kidnapping and raping the 38-year-old woman, who allegedly spent a week locked in the bunker in Kristianstad, in the country's south, late last year.

New details have emerged about Dr Trenneborg, who has been compared to Josef Fritzl, the Austrian man who kept his own daughter locked up in a cellar for 24 years.

Dr Trenneborg studied to become a doctor at the prestigious Karolinska Institute in Stockholm, before working as a GP in Stockholm and Kristianstad, German newspaper Bild reported.

Dr Trenneborg also claims to be a member of Mensa, an international organisation for people who attain a score within the top 2 per cent of the general population on an approved IQ test.

A man who claimed to be a friend of Dr Trenneborg told Swedish daily newspaper Kristianstadsbladet that he was always helpful, nice and extremely intellectual.

"He is a head man. He does not speak about feelings and tries to solve everything intellectually," the anonymous friend was quoted as saying.

Images on Dr Trenneborg's Facebook page show him mountain climbing, while, on a blog, he wrote that his favourite actors were Christopher Walken, Arnold Schwarzenegger and Italian porn star Rocco Siffredi, Bild reported.

Prosecutor Peter Claeson told Swedish newspaper Aftonbladet that Dr Trenneborg spent several years building the bunker, which was about 60 square metres in size and sound-proof and light-proof.

It is not clear how Dr Trenneborg was introduced to the woman, but they spoke on the phone for the first time on September 10 last year, Kristianstadsbladet reported.

Two days later, they met in person at the woman's Stockholm apartment, where Dr Trenneborg allegedly drugged her with Rohypnol-laced strawberries, before using a wheelchair to take her to his car and driving her more than 550 kilometres to the bunker.

He allegedly wore rubber masks of bearded and elderly men during the journey to avoid being recognised.

The woman is reported to have been handcuffed for most of the six days of her incarceration and raped repeatedly, according to CNN.

Aftonbladet reported that the doctor allegedly acquired the contraceptive pill, as well as equipment to test if the captured woman had a sexually transmitted infection. He allegedly tested the woman's samples at his work.

After six days, Dr Trenneborg reportedly drove back to Stockholm to retrieve some of the woman's belongings from her apartment, when he discovered she had been reported missing.

Dr Trenneborg's barrister, Mari Schaub, told Bild that her client found a piece of paper taped to the woman's front door that read: "We miss you".

"Someone had searched for the woman. That was the last straw," she said, the newspaper reported.

Dr Trenneborg then took the woman to a police station in Stockholm on September 18, hoping to persuade police that she was unharmed and that they were a genuine couple, according to The Local, an English-language newspaper in Sweden.

However, officers became suspicious and spoke to the woman separately. She told them that she had been kept prisoner.

The newspaper reported that Dr Trenneborg admitted drugging the woman and taking her to his home, but denied raping her. He also wanted the kidnapping charge to be reduced to a less serious charge of deprivation of liberty.

"He is a man who was mentally depressed and, when at the police station, complied with all the requests of the police," Ms Schaub told CNN.

"He is very much in regret of what he has done."

When police searched the bunker, they allegedly found a simple Ikea pine bed, a desk and a kitchen area with a sink and hot plate, as well as a fridge stocked with fresh food.

Dr Trenneborg's trial is due to start in the Stockholm District Court on Monday, local time.