MINNEAPOLIS (AP) — Investigators searched a central Minnesota property Wednesday where an 11-year-old boy was abducted at gunpoint nearly 21 years ago and never heard from again.

Authorities said little about the search in St. Joseph. But aerial photos taken by the St. Cloud Times showed as many as 17 vehicles, all-terrain vehicles and trailers on the property.

Stearns County Chief Sheriff’s Deputy Bruce Bechtold told The Associated Press an investigation was being conducted, but that a court order restricted him from discussing details. FBI spokesman E.K. Wilson said the FBI was assisting in search warrant operations in the area. He would not elaborate.

A woman who lives at the property hung up on a reporter who called seeking comment.

Jacob was riding his bicycle with his brother and a friend on Oct. 22, 1989, and was just a half-mile from his home when they were approached by a masked man with a gun. The boys said the man took Jacob, and he has been missing ever since. There have been no arrests.

Jacob’s mother, Patty Wetterling, said the investigation into her son’s disappearance is still open. She wasn’t aware of any big “break” in the case that led investigators back to the property in St. Joseph.

“I know that what you do with an older case, is you go back to the beginning and you revisit everything, and that’s what I believe they’ve done,” Wetterling said. “So, you go back to the center. This is where it all started.”

“Hats off to all of the investigators involved. They are doing what they can,” she added.

Wetterling became a nationally known advocate for missing children after her son’s disappearance. She helped pass federal and state laws to track sex offenders and alert the public when children go missing. She and her husband also founded the Jacob Wetterling Foundation, now known as the Jacob Wetterling Resource Center, in 1990.

Wetterling attributed Wednesday’s search to “good cop work” but said it still was heartbreaking, both for her family and for the family that owns the property, saying they have also been through a hard journey.

“You stay steady,” Wetterling said. “That’s what you have to do to survive.”

Nancy Sabin, the former executive director of the Jacob Wetterling Resource Center, said through the years authorities have cleared more than 40,000 leads in Jacob’s case.

Wetterling said she is grateful that authorities are still searching for her son, and hoped that the search would at least allow investigators to rule people in or out as possible suspects.

“I’m grateful people still care,” Wetterling said. “They still care. They’re still searching. Nobody’s forgotten.”