The FBI released documents from its vault Wednesday on the bureau's short-lived investigation into Bigfoot in 1977.

The 22 documents show that the bureau’s Scientific and Technical Services Division examined 15 hairs sent by Peter Byrne, who was head of the now-defunct Bigfoot Information Center and Exhibition in Oregon.

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“Will you kindly, to set the record straight, once and for all, inform us if the FBI has examined hair which might be that of a Bigfoot,” an August 1976 letter from Byrne says. “Please understand that our research here is serious. That this is a serious question that needs answering.”

Jay Cochran, then assistant director of the division, wrote back that while the bureau primarily examines criminal investigations, “on a case-by-case basis, in the interest of research and scientific inquiry, we make exceptions to this general policy.”

The hairs were examined in 1977 and determined to be of deer origin.

Byrne, now 93, told CNBC Wednesday he hasn't given up hope on the existence of Bigfoot.

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The documents were originally obtained through a Freedom of Information Request.