Approximately 100 brain specimens stored at the University of Texas at Austin have mysteriously gone missing.

The Associated Press reported that the specimens were in jars of formaldehyde and one of the missing brains is believed to be that of clock tower sniper Charles Whitman.

Whitman was an ex-Marine who shot 46 people and killed 16 in a rampage at the university back in 1966.

It’s puzzling why someone would want to steal the brains, but as West Texas News noted, psychology professor Lawrence Cormack believes they may have been taken as part of a Halloween prank.

"It's entirely possible word got around among undergraduates and people started swiping them for living rooms or Halloween pranks," he said.

Around 200 specimens were first transferred from the Austin State Hospital to the school under an agreement several years ago. Only half of the brains fit in the psychology laboratory so the rest were kept in the basement of the university and that’s where they went missing from.

The school has said that it is investigating the incident.