The FBI said there are only two things that would cause them to reopen the case - if one of the parachutes was found or more money from the $200,000 ransom.
The FBI has closed the case on DB Cooper, the well-dressed hijacker who disappeared out the back of a Northwest Orient Airlines jetliner between Portland and Seattle in November 1971.
During the course of the 45-year NORJAK investigation, the FBI exhaustively reviewed all credible leads, coordinated between multiple field offices to conduct searches, collected all available evidence, and interviewed all identified witnesses.
Some "D.B.Cooper cash" is displayed at Collectors Universe Tuesday Feb. 12, 2008 in Santa Ana, Calif. Brian Ingram, from Arkansas, found the sole link to the only unsolved airline hijacking in USA history buried along the Columbia River during a family vacation in 1980.
The famed police sketch showed a bespectacled man of average height, wearing a sport jacket and thin tie, fashion very much of the iconic, buttoned-up era in 1950's and 60's business. For you youngsters out there, think of DB Cooper as a really rare Pokemon that no one has ever caught.
More than 800 suspects were interviewed by the hijacking's fifth anniversary.
Investigators thought they cracked the case when they arrested Richard Floyd McCoy, who was suspected in a very similar airplane hijacking and escape by parachute, which occurred less than five months after Cooper's.
During the flight, he gave a flight attendant a note indicating he had a bomb in his briefcase and wanted her to sit with him, and she obeyed. After the plane landed in Seattle, Cooper received what he asked for in exchange for the flight's 36 passengers.
In addition, Gray - author of "Skyjack: The Hunt for D. B. Cooper", published by Broadway - says a quirk in the statute of limitations laws means that "in theory, if Cooper were to walk out of the woods today, he could theoretically be charged with a crime".
That evidence includes the hijacker's black tie and a crumbling package of $20 bills matching the ransom money's serial numbers.
But none of the tips led to "proof beyond a reasonable doubt" linking any suspect to Cooper, the Federal Bureau of Investigation said.
"The fascination with Cooper has survived not because of the FBI investigation, but because he was able to do something that not only captured the public imagination, but also maintained a sense of mystery in the world", Gray said.
The FBI said it is still encouraging anyone with new information or possible evidence - such as the parachutes or ransom money - to come forward.