The FBI has what it calls "our most promising" lead to date for a suspect in the infamous 1971 D.B. Cooper case – the nation's only unsolved commercial airplane hijacking.

The name of a man not previously investigated was given to the FBI, and an item that belongs to him was sent for fingerprint work at the agency's Quantico, Va., forensic lab, agency spokeswoman Ayn Sandalo Dietrich told seattlepi.com Saturday.

A law enforcement colleague spoke with someone who may have a strong connection to Cooper, and that law enforcement staffer contacted the FBI, Sandalo Dietrich said.

"With any lead our first step is to assess how credible it is," said Sandalo Dietrich, spokeswoman for the FBI's Seattle office, where the Cooper evidence is kept. "Having this come through another law enforcement [agency], having looked it over when we got it – it seems pretty interesting."

Sandalo Dietrich, who was out of the office Saturday, did not have the date when the information was given to the FBI. She also didn't give specifics about the item, citing the ongoing investigation.

"It's back at our lab and we hope to compare it to partial fingerprints we got in the hijacking," Sandalo Dietrich told seattlepi.com. "It would be a real break if it came back."

However, agents are not sure if fingerprints can be pulled from the item.

The FBI has not released the suspect's name, age, hometown or possible criminal record. However, the item being sent to the forensic lab appears to be a significant step.