STOCKHOLM (Reuters) - A Swedish doctor went on trial in Stockholm on Monday on charges of kidnapping and raping a woman whom prosecutors said he planned to hold prisoner for years in a specially constructed soundproof bunker.

Swedish doctor Martin Peter Trenneborg (L) is seen next to his lawyer Mari Schaub in this courtroom sketch received by Reuters January 25, 2016. REUTERS/Ingela Landstrom/TT News Agency

Martin Peter Trenneborg, who held the woman for six days, has admitted to kidnapping her but denies the rape charge, according to police reports made available to journalists.

His plan went awry when he went to the woman’s apartment to get some things for her and discovered the lock had been changed. He brought her to the police with instructions to say she was not missing and get the new key, the documents showed.

But the woman seized the opportunity to seek protection from the police and they arrested Trenneborg. The documents did not indicate why he thought she would not try to break free.

The documents said the doctor, 38, had given the woman strawberries spiked with a “date rape” type sedative in Stockholm and brought her to the bunker in his isolated house in southern Sweden, about 550 km (340 miles) away.

“He said he was planning to hold me there for a couple of years and then I panicked and my whole body started to shake,” the woman in her 30s told police during questioning.

She said that told her: “You can scream as much as you like, but no one is going to hear you.”

In an interview at his office, chief prosecutor Peter Claeson told Reuters: “This man is charged with drugging a woman in Stockholm, he has had sexual intercourse with her while she was unconscious or slept, and abducted her to his residence outside Kristianstad.

“The man has told us that he intended the woman to become his girlfriend and she was to stay there for several years.”

Prosecutors believe he also planned to kidnap other women.