UNDATED (USA TODAY) -- About one-third of the world's largest collection of autism brain samples have been damaged because of a freezer malfunction at Harvard-affiliated McLean Hospital in Massachusetts, The Boston Globe reports, quoting scientists involved with the program.

The freezer shut down in late May without triggering two alarms, The Globe says, quoting an official at the renowed brain bank in Belmont.

As a result, 150 thawed brains had turned dark from decay, including about 50 that were part of a collection of autism brains owned by the advocacy and research organization Autism Speaks.

"This was a priceless collection,'' Dr. Francine Benes, director of the Harvard Brain Tissue Resource Center where the material is stored, tells the newspaper. "You can't express its value in dollar amounts."

The newspaper quotes one expert as saying the damage could slow autism research by a decade as the collection is restored.

Benes, who is leading one of two internal investigations into the freezer failure, tells The Globe that the circumstances -- in which both an alarm and a thermostat would fail -- are so unusual that she cannot rule out foul play.