On Nov. 24, 1971, a man boarded a commercial plane in Portland and jumped into history as one of the FBI’s most sought-after criminals. Today, the D.B. Cooper case remains unsolved — but that doesn’t mean the mystery has gone stale.

Citizen sleuths and scientists still search for whispers and clues to help unravel the truth behind the daring hijacking of Northwest Orient Flight 305. Whether the man who stole $200,000 in cash and parachuted out of the back of the plane into a forest survived may never be known, but his legend lives on at CooperCon.

True-crime investigator Eric Ulis spearheads the convention in Vancouver, which is billed as “the world’s only annual event focused on the legendary 1971 skyjacking and mystery — the only unsolved skyjacking in US history.”

The fourth annual CooperCon will take place Friday, Nov. 18-Sunday, Nov. 20 at Kiggins Theatre. Each day is packed with a lineup of debates and presentations, covering everything from the $5,800 found in 1980 in Clark County to Hollywood’s interpretation of the infamous events. There’s even a session on the PNW’s other legend… Bigfoot.

Eric also manages a dedicated Facebook page where its 3,200+ members can tune into regular live streams, chime in on discussion threads (who you would cast to play the skyjacker in a movie?), and share theories.

The FBI closed the book on the NORJAK case in 2016. If there are any answers still out there, they’ll need to be unearthed by dogged enthusiasts or someone in the right place at the right time, which brings us to this: It’s widely believed that Cooper jumped near Ariel, Washington. The remaining sum of $20 bills was never recovered and though an old strap was found in recent years, it seems the parachute is still missing.

Anyone who finds such evidence is asked to contact their local FBI field office.