The Olmsted County Sheriff's Office has uncovered a clue in the strange case of the $500,000 jewel heist off I-90 last week.

Capt. Scott Behrns said in an email today that authorities recovered one of the cases stolen during the robbery of a group returning from a jewelry trade show in Chicago. The group had stopped at a rest area just after midnight on Dec. 8 when a van pulled up, four men jumped out and smashed in the victims' windows to grab cases of diamonds and other gems. Then they tore off.

The case was found near the intersection of Olmsted County Road #7 and Highway 52 Southeast in Orion Township without any jewelry inside, though it did have jewelry display items, according to Behrns. The materials are being sent to the Minnesota Bureau of Criminal Apprehension Crime Lab for analysis, he said.

The perpetrators are still at large.