Belmont police said the circumstances leading up to Ylva Hagner's 1996 disappearance are still unknown after leading a search at two sites on Farm Hill Boulevard in Redwood City last week.

The Belmont Police Department, along with local authorities and the FBI, searched Stulsaft Park and a home on the 3700 block of Farm Hill Boulevard on May 10 for evidence related to the unsolved missing person case of 42-year-old Ylva Hagner who disappeared over 25 years ago.

"Investigators are actively working on this case and have conducted numerous interviews and collected several items from various searches. The circumstances leading up to the disappearance of, and the whereabouts of, Ylva Hagner are still unknown," said Belmont police Lt. Pete Lotti said in a May 12 press release.

As of May 17, there have been no other updates, Lotti told this news organization. "Our detectives and investigators are still getting caught up on everything since last week," Lotti said.

Hagner was last seen by coworkers in her office in Belmont on October 14, 1996. Her unlocked vehicle was found four days later in San Carlos with her keys in the ignition, six blocks from her workplace. Authorities said in multiple missing person reports that Hagner's purse was missing and there was no sign of a struggle in the car.

According to multiple missing person reports, Hagner lived in Palo Alto and attended Stanford University. According to her family, Hagner had been stalked by a male acquaintance before her disappearance, a missing person report said. She worked as a business-marketing manager for a German-American software company called iXOS.

The investigation is active and ongoing, and more updates will be provided as information becomes available, Lotti said.

The Belmont Police Department is asking the community to call its tip line at 650-598-3000 with any information that would help resolve this case. Callers have the option to remain anonymous.