Police on Tuesday searched for possible undiscovered hidden rooms at the house where a kidnapped schoolgirl was imprisoned in an underground cell for more than eight years, authorities said.

Twelve officers combed through the house in Strasshof, a tidy suburb just northeast of Vienna, checking the home's construction to rule out the possibility that Wolfgang Priklopil may have built other windowless cells, the Federal Criminal Investigations Bureau said.

Investigators have not suggested that Priklopil, 44, kidnapped other girls besides 18-year-old Natascha Kampusch, who escaped on Wednesday. Hours after she got away, Priklopil killed himself by throwign himself under a commuter train.

So far, authorities said Tuesday, police have uncovered no other hidden cavities in the house.

The house is large and the search -- complicated by the fact that some of the blueprints are missing -- could take several days, the Austria Press Agency quoted an unidentified investigator as saying.

CountryWatch: Austria

Officials have said that Priklopil's DNA was checked against a vast nationwide database and there was no evidence that he had been sought for any other crimes, including other missing person cases.

Police said they had not yet resumed their questioning of Kampusch, who remained in a secure and undisclosed location, adding that it was "up to her and her alone" to decide when she was ready to talk to investigators about her ordeal.

Guenter Harrich, a Vienna lawyer, said he was to meet again with Kampusch on Tuesday afternoon to go over her rights to financial assistance. Harrich said he would take her some cosmetics she had asked for and that a psychiatrist already had given her euro50 (US$64) because she had no pocket money.

"She is a sweet, very nice, clever woman with an unbelievable intellect" and has been busy writing, reading and painting, Harrich was quoted as telling the APA agency.

Kampusch was 10 when she was abducted on a Vienna street while walking to school on March 2, 1998. Until last week, when she bolted to freedom while Priklopil was busy with a cell phone call, her disappearance had been one of Austria's greatest unsolved criminal mysteries.

State broadcaster ORF on Tuesday aired an interview with a neighbor, Josef Jantschek, who claimed he saw Kampusch riding with Priklopil in his car on several occasions in recent months.

"She looked friendly, but pale," Jantschek said, adding that he also saw the young woman in the garden of Priklopil's home and thought it was odd that she always entered the house through the garage -- where police say hidden stairs led to the cell.

Jantschek said he asked Priklopil if the woman was his friend, and was told she was a housekeeper from the former Yugoslavia.

Austria's Justice Ministry said Tuesday it planned to toughen the penalty for kidnappers who imprison their victims. Had Priklopil not committed suicide, he would have faced a maximum sentence of 10 years -- only 18 months longer than Kampusch was held.

Police images of the basement cell where Kampusch was kept showed the room contained, among other things, books, clothes, a television, a bed, a toilet and a sink. Investigators say she also was allowed to listen to the radio and watch some videos, and with the help of a book, taught herself how to knit.

On Monday, Kampusch issued a statement saying she mourned "in a certain way" for the man who enslaved her and did not feel she had missed out on much during her 8 1/2 years in captivity.

Her statement -- which surprised many people with its eloquence -- suggested she may be suffering from "Stockholm Syndrome," in which victims cope with insufferable situations by identifying with their captors.

Kampusch described her cell as "my room" and Priklopil as "a part of my life," adding, "That's why I also mourn for him in a certain way."