JANESVILLE, Wis. — Investigators began digging up an empty lot in Janesville on Monday after receiving a tip about the 1947 cold case of an 8-year-old girl who disappeared from her family's farm in neighboring Jefferson County.

The Rock County Sheriff's Department said in a statement that an individual provided some information to detectives last month, and they were checking it out. Authorities did not disclose details.

According to the Jefferson County Sheriff's Office, the case involves Georgia Jean Weckler, who went missing May 1, 1947. She was last seen being dropped off by a neighbor after school at her parents' farm near Fort Atkinson. The driver saw her get mail from the mailbox, but the girl also told her neighbor she wanted to go into the woods to pick flowers. She was never seen again, the sheriff's office said in a statement.

Authorities from both counties were at the scene on Janesville's far northeast side Monday, along with a canine search-and-rescue unit. Crews were digging holes and sifting through buckets, The Janesville Gazette reported (http://bit.ly/16pBtGe ).

Capt. Jerry Haferman of the Jefferson County Sheriff's Office told The Associated Press they were working "shovel by shovel" and that the search would likely take a long time. He said crews expected to keep working until dark and resume digging Tuesday.

A Gazette story that ran on the 20th anniversary of Georgia's disappearance said it led to one of the most intensive hunts in the history of the area at the time.

A Richland Center man, Buford Sennett, serving a life term at the Waupun state prison for a different 1947 murder and kidnapping, confessed to abducting and killing Georgia but changed his story several times and was never charged.

Then-Jefferson County District Attorney Francis Garity and Undersheriff Roger Reinel tended to believe Sennett's story that he kidnapped the girl with two accomplices for ransom but fed her an overdose of sleeping pills and dumped her body in the Blue River, the newspaper reported.

"Garity died believing the confession was true. But Sennett changed his story several times. Once he said the body was buried, but police dug up the ground he led them to and never found the body. He took police to the Blue River, but divers couldn't find the body. And Sennett refused to sign a statement," the 1967 story said.

Sennett died in 2008 shortly after he was transferred from the Dodge state prison to a supervised living facility, according to Wisconsin Department of Corrections records, spokeswoman Joy Staab said. He was 82.

Reinel told the Gazette in 1967 about the case: "I don't imagine it will ever be closed. It will always be on file."