correction

An earlier version of this story misstated the number of people convicted in connection with the theft of parts from the jet and the relationship between two of them. Three people were convicted in the case. A TWA pilot pleaded guilty to theft of government property. A former TWA flight attendant instructor and her husband were found guilty of conspiracy, and aiding and abetting in the theft.

For nearly 20 years, a haunting relic of one of the worst aviation disasters in U.S. history has been tucked away in a cavernous warehouse in Northern Virginia.

The fuselage of the Boeing 747, painstakingly reassembled from nearly 1,600 pieces plucked from the depths of the Atlantic Ocean, is a macabre jigsaw puzzle of wires and burned, twisted metal. But it is all that remains of Trans World Airlines’ Flight 800, the Paris-bound jetliner that crashed shortly after takeoff from New York’s John F. Kennedy International Airport 25 years ago Saturday killing all 230 people onboard.

The crash made headlines for years, the tragedy of the loss compounded by suspicions the plane may have been the target of a terrorist attack. Ultimately, after a four-year investigation, the National Transportation Safety Board concluded the cause was an explosion in the plane’s center fuel tank, the result of a flammable mix of fuel and air ignited by a spark.

The NTSB is set to close another chapter in the story of TWA 800. The downed jetliner, one of a handful recovered and reconstructed, was decommissioned this month and will be destroyed by the end of the year.

Since 2003, when the wreckage was moved from New York to the agency’s training center in Ashburn, it has been used to help first responders and transportation safety investigators. But advances in technology for investigating crashes — coupled with the end of the lease on the hangar-like space where the 93-foot-long, 60,000-pound reconstructed hulk is housed — led the NTSB to conclude it is no longer practical to maintain.

The news brought mixed reactions from family members and friends of those who died in the crash.

Heidi Snow Cinader — who was 24 when she lost her fiance, Michel Breistoff, a professional hockey player — said despite the horrors of the crash, the plane held a special significance for some and provided a measure of comfort for others.

“It’s important to have something tangible and a place to go to understand what had happened,” said Cinader, who later founded the nonprofit AirCraft Casualty Emotional Support Services, which helps people who have lost loved ones in plane crashes. “It’s been important for all of us to have the plane there, but it’s understandable that it can’t be there forever.”

An agreement between the NTSB and TWA 800 families to move the jet to Virginia specified the remains be used only for training purposes, keeping the shattered jetliner largely shielded from the public even as it has been available for loved ones to view. Many have viewed the wreckage over the years, but that number dwindled as time passed, said Sharon Bryson, the NTSB’s managing director.

For Larry Gustin, whose mother, Anne Gustin, died in the crash, seeing it once was enough.

Gustin, a retired pediatrician from Tampa, said he remembers seeing the wreckage up close, standing in the jet’s cabin next to the seat his mother occupied on what would have been her first trip to Paris. Anne Gustin planned to go sightseeing and visit her youngest son, who had moved to France.

“I have kind of mixed feelings,” Gustin said of the decommissioning. “Especially this being the 25th year. We are losing something that’s always been there.”

For many families, the reconstruction also stood as a reminder of birthdays, anniversaries and graduations that would never be celebrated, of smiles frozen in photographs and family movies. Over the years, some have asked to place small tokens on the seats their loved once occupied.

“After 25 years, family members realize it’s a reasonable amount of time for them to let it go,” said James Hall, who served as chairman of the NTSB during the TWA 800 crash and investigation. “Nevertheless, it’s bittersweet.”

Recovering and rebuilding the jetliner that exploded 12 minutes after departure was a herculean effort, a feat that had been done in only three previous crashes, including Pan American Flight 103, which was shattered by a bomb over Lockerbie, Scotland.

Some debris from the explosion of TWA 800 hung in the air for 20 minutes before falling into the waters off Long Island, the NTSB said. Eyewitness reports of “flare-like” objects near the jetliner before it burst into flames made its recovery crucial to the investigation, which also involved the FBI. The recovery process included more than 200 divers, 14 ships and a fleet of remotely operated vehicles.

More than 95 percent of the wreckage was recovered, an effort that took more than 10 months. The pieces were taken to hangars on Long Island spread across an area that spanned seven acres.

Frank Hilldrup, an NTSB investigator who was involved in the TWA 800 recovery, said looking at the wreckage still fuels his sense of purpose.

“It reminds you what you’re doing and who you’re working for,” said Hilldrup, now the NTSB’s chief technical adviser for international aviation. “It illustrates the lengths you have to go to sometimes to really tell the story, to prove the story, to support the recommendations.”

For Bryson, the remains of TWA 800 are a reminder of what was lost that July night.

The 230 people came from 14 countries. The victims included 16 students, members of the French Club at Montoursville Area High School in Pennsylvania, and their five chaperones. There also was a French guitarist and an American composer.

The crash and subsequent safety recommendations changed how airplanes are built and designed.

In 2004, the Federal Aviation Administration ordered that airplanes be retrofitted with systems to reduce the volatility of the mix of air and fuel in tanks, a decision the NTSB called, “a transformational improvement in aviation safety.” The vulnerability was identified as a factor in airplane crashes in the early 1960s. The investigation also led to the creation of a system at the FAA to address aging aircraft systems, such as wiring.

The crash also shined a light on the human impact of air disasters, spurring the creation of a formal program at the NTSB focused on supporting families.

“I hope that the family group from this accident understands that through all the loss — the tremendous loss that occurred — all the good that occurred,” Bryson said. “After our recommendations, we saw no more accidents like this. It taught us to work better with our partners. And today, people benefit so much from that relationship, and certainly the Family Assistance Act has changed not just transportation, but family assistance around the world.

When the time comes later this year, what remains of TWA 800 will be taken apart and melted, burned or shredded. Those involved in the work will be required to sign nondisclosure agreements. Parts that aren’t destroyed must have any marks removed that could identify them as being part of TWA 800, NTSB officials said.

The precautions are to avoid having pieces fall into the hands of someone who might try to profit from or exploit the crash, as happened in 1999 when three people were convicted in connection with the theft of parts from the plane.

Since 2002, the families have had another place to reflect and remember those lost on July 17, 1996: the TWA Flight 800 Memorial at Smith Point County Park, near where the plane crashed. Names of the 230 victims have been inscribed on a memorial wall, along with the quote: “A labor of love for all those lost and those who must remember … find comfort here.”

“It’s a beautiful spot that provides people with a place to reflect,” said Frank A. Lombardi, chief operating officer of IGHL, a Long Island-based nonprofit that worked with the families to build and maintain the memorial.

On Saturday, Lombardi will join family members for an annual ceremony that has followed a familiar but comforting script. At the end of the program, families will be presented with 230 white carnations — one for each person who lost their life.