A 1971 artist's sketch released by the FBI shows the skyjacker known as “Dan Cooper” and “D.B. Cooper,” from the recollections of passengers and crew of a Northwest Orient Airlines jet he hijacked between Portland, Ore., and Seattle, Nov. 24, 1971. (AP)

The FBI, in its bang-up summer of solving cases, has a new lead on a 40-year-old case. The agency has a credible lead on a man who may be the infamous D.B. Cooper. His story captured the U.S.’s imagination when, in 1971 just before Thanksgiving, a man who gave his name as “Dan Cooper,” boarded a plane in Portland and “stepped into the night sky” somewhere over the Pacific Northwest. In between, he had hijacked the plane and extorted $200,000 and two parachutes from the government.

The FBI told the Seattle Times that it was a promising lead, but not to expect the case to break at any minute.

I went back in the Post’s archives to find the original story, written on Nov. 25, 1971, about D.B. Cooper. It’s the stuff of movie magic (see below). One fact that jumped out at me in the article: Passengers didn’t even know they were being hijacked until Cooper released them. Read all about it here:

The FBI began a massive manhunt in four Western states today after a middle-aged man stepped into the night sky from the rear door of a hijacked jetliner, wearing a parachute and carrying $200,000 in ransom money.

By sundown today, authorities still did not know who the man was, whether he had accomplices, where he had landed or if the parachute — possibly furnished by the U.S. Air Force — had opened.

Nobody saw him go — the crew was locked in the forward compartment of the Boeing 727 — and nobody really believed he had gone until the plane, airport and surrounding countryside were searched with dogs at Reno, Nev., the last stop.

The Air Force had three planes tailing the jetliner during part of its odyssey, one of them a C-130 transport, which reportedly carried para-troopers, although an Air Force spokesman later dismissed that report.

The plane was Northwest Airline’s Flight 305, which originated in Washington, D.C., on Wednesday and stopped at Minneapolis; Great Falls and Missoula, Mont.; Spokane, Wash., and Portland.

At Portland, a man identified only as D.B. Cooper boarded the plane, which by then had 36 passengers and six crew members, and a few minutes later, on the way to Seattle, opened his briefcase and amiably showed a stewardess a device of red cylinders and wires, and handed her a note demanding the $200,000 and two parachutes.

At 4:50 p.m. PST, the plane went into a holding pattern over Seattle as ground control at the Seattle-Tacoma International Airport began discussing the matter with the crew of the 727.

Police and the FBI agreed that no action should be taken, and Northwest officials set about getting the money from local banks. Nearby McChord Air Force Base agreed to furnish the parachutes, and when everything had been gotten together, Cooper — who by now was described as edgy and not as calm and relaxed as he had been earlier — ordered the plane to land and park in a lighted area.

At 5:45 p.m. the plane touched down in Seattle. Cooper allowed the 36 passengers — most of them did not know they had been hijacked until that instant — to leave the plane along with two stewardesses.

The money and parachutes were brought out to the plane, which had been refueling, and Cooper then ordered the pilot Capt. William Scott to fly to Mexico, low and slow with the rear door open and the steps down.

Cooper at first had ordered two parachutes, which were brought out from McChord. They were the military type, which must be opened with a static cord linked to the plane. It would open the chute after a 200-foot fall.

Cooper then ordered two more. Airline officials did not say whether Cooper specified the type, but the second set were sports models, obtained at a skydiving field east of Seattle. A sports ‘chute’ would allow a man to free-fall several thousand feet before opening the parachute.

After the plane landed, two of the four parachutes were found aboard. officials would not say what type they were.

FBI and police reports indicate that the plan was carefully thought out. The man apparently knew enough about airliners to know that the 727 is one of the few commercial jets from which it would be possible to parachute safely.

He also ordered the pilot to fly low, with full flaps, at 200 mph, the only way the normally pressurized jetliner could fly with the rear door open. (At that, it was reported by the four crew members who remained aboard that the temperature inside the plane dropped to below zero.)

Cooper’s destination, he said, was Mexico City, 2,200 miles away. The maximum range for the 727 the way Cooper wanted it flown Wednesday night is about 1,000 miles, and in conference with the crew Cooper decided that it would be all right to stop for fuel in Reno, with a second stop later at Yuma, Ariz.

The plane took 3.5 hours to loaf along to Reno, with the crew locked in up front.

The route took the plane over the Willamette Valley, a broad, flat farmland area where a parachutist could land safely even at night, rather than over Oregon’s rugged Cascade Mountains, where temperatures were below freezing and snow warnings were posted today.

When the plane landed in Reno at 11 p.m. Wednesday police with dogs searched the darkened runways of the Reno airport, a residential section and a desert area nearby, and assured themselves that there was “no way” Cooper could have deplaned unseen at the airport. But he was not on the plane either.

Early today airplanes and helicopters were sent to the Lake Merwin area in southwestern Washington State to begin the search for the middle-aged, swarthy hijacker, who wore sunglasses throughout his trip.

All [crew members] were unharmed when they arrived in Reno, but cold.