They got a search warrant. They used cadaver dogs. But they came up empty-handed.

A review of the case files in the disappearance of 9-year-old Scott Kleeschulte had given St. Charles police investigators a glimmer of hope about solving the 23-year-old mystery.

Their actions are a snapshot of the way these cases are handled. They get handed down from detective to detective. They aren't allowed to go cold.

St. Charles Police Lt. Mike Akers declined to say specifically what information spurred the most recent search, which happened at the end of November at a home in Kleeschulte's neighborhood. Akers would say only that it had come from a comment in an old interview.

"We feel now that maybe this person wasn't very reliable or wasn't giving us good information," he said.

Neighbors said authorities drilled holes through the concrete in the garage and other areas around the home in the 3400 block of Leverenz Drive. Akers said the dogs did not detect anything.

Kleeschulte has been missing since June 8, 1988. He was last seen not far from his home walking near a wooded area known as "The Trails" just before a fierce thunderstorm swept through the area.

As long as six weeks after his disappearance, police conducted large-scale searches of the area near the Kleeschultes' home. The searches involved digging — with bulldozers and shovels — at a labyrinth of caves in the wooded hillside where Scott was known to play with other neighborhood children. Bloodhounds, sophisticated ultrasound equipment, helicopters and volunteers were used to scour creeks and sewers. Tips provided by psychics were checked out.

Akers said he wouldn't comment further about the recent search because the information is sensitive.

The search warrant was sealed for 120 days by St. Charles County Circuit Judge Nancy Schneider. She could not be reached for comment.

Attempts to reach the property owner, who now lives in the Troy, Mo., area, were unsuccessful.

Kleeschulte's family still lives in the same tidy ranch home as it did in 1988, a few doors from the house that was searched. They declined, through authorities, to be interviewed.

Akers said that even though new tips don't often come in about the case, the investigation files are regularly reviewed.

"We're always looking at them and saying 'Did I miss anything?' " Akers said. "Every now and then you'll get a new lead."

In Lincoln County, where investigators have two longstanding missing child cases — Arlin Henderson, who disappeared July 25, 1991, and Bianca Piper, who was last seen on March 10, 2005 — officials expressed a similar passion about getting the cases solved.

"We do not give up on these cases," said Lincoln County Sheriff Mike Krigbaum. "We investigate any leads that come in. Who knows? Arlin Henderson or Bianca Piper may show up one of these days."

Akers said he had only been on the St. Charles police force about two years when Kleeschulte disappeared. He never was the lead investigator, but he was among those who searched.

"I spent two days in the woods chasing bloodhounds looking for that little boy," he said.

It was the first missing child case he worked that police didn't solve. Akers said he keeps a photo of Kleeschulte on his desk as a reminder not to give up.