Theft happens at card shows, but one dealer was the victim of a major heist at last weekend’s East Coast National show at the Westchester County (NY) Center when someone walked off with his 1955 Topps Roberto Clemente rookie card graded PSA 8. The card is worth $20,000-$30,000. It was inside an unlocked case on the dealer’s table at the show when the incident took place on Saturday.

Here are photos of the front and back, courtesy of long-time hobbyist and friend of the victim, Dan McKee.

McKee says the victim typically keeps his cases locked but was momentarily sidetracked by other customers and the thief apparently took advantage.

While the card may well be cracked out of the case and offered for sale or resubmitted to a grading company, McKee urged collectors to examine the card’s centering and other qualities in case they’re offered a Clemente rookie.

No description of the suspect was available.

According to witnesses, other thefts took place Friday at the show and one man was arrested after being chased down by a dealer.