FOND DU LAC, Wis. (CBS 58) — Investigators are excavating additional locations in southeast Fond du Lac County as they continue searching for answers in the 1983 disappearance of Robert "Bobby Jo" Fritz.

The Fond du Lac County Sheriff's Office said the sites have been identified as areas of interest that could contain evidence related to Bobby Jo's disappearance, which has remained unsolved for more than 43 years.

Earlier in 2026, detectives excavated the Campbellsport property where Bobby Jo lived at the time he disappeared. Investigators recovered several items of interest and potential evidence during that search.

Those items were sent to a private laboratory for analysis, and results remain pending.

The sheriff's office said investigators continue to pursue every credible lead and follow up on new information received in the case.

Authorities said additional details will be released when doing so would not compromise the integrity of the ongoing investigation.

Bobby Jo disappeared May 14, 1983. He was last seen playing outside with his siblings between approximately 2:30 and 4:30 p.m.

He was last seen wearing a red, blue and gray shirt, blue pants and boots.

Bobby Jo has a 2-inch-by-3-inch red birthmark on his outer left thigh above his knee. Authorities have also said he had difficulty pronouncing the letters "T," "K" and "R."

The Fond du Lac County Sheriff's Office said it remains committed to determining what happened to Bobby Jo and providing answers to his family.