The man, whose name was not reported, told the Rock County sheriff's department and the Janesville Police Department July 30 he remembered "suspicious activity in the area of East Rotamer and Wright roads in Janesville" on May 1, 1947, the day the girl, Georgia Jean Weckler, disappeared.
Weckler was last seen in the driveway of her home after she was dropped off from school. Neighbors at the time reported seeing a "suspicious 1936 dark-colored Ford" in the area, but no evidence was collected and the girl was never found, said Capt. Jerry Haferman of the Jefferson County sheriff's office.
The sheriff's offices received leads over the years, the last one being in 1999, but the girl's body never turned up.
Haferman told the Milwaukee Journal Sentinel police began a dig effort in the area described by the tipster after a K-9 unit detected possible human remains Monday.
"We have just started to dig," Haferman said. "Sifting through everything: dirt, trees. It could take hours or days."
The captain said he didn't know why the tipster is only just now coming forward with information.
"He said he just put two and two together."