LONGMONT, Colo. — The windows shook as dynamite aboard an airplane exploded over Conrad Hopp’s family farm in northern Colorado 70 years ago.
Hopp, then 18 years old, saw a ball of fire streaking across the night sky and rushed with his brother toward where the burning wreckage came down, dodging objects that turned out to be the bodies of victims of the first confirmed case of sabotage against a commercial U.S. airliner.
Hundreds of miles away, Marian Poeppelmeyer’s mother, pregnant with her, was at home in Pennsylvania when she learned her husband was among the 44 people killed in the bombing. She ran upstairs and held her oldest daughter tightly and screamed, Poeppelmeyer said, recounting a story told by her mother soon before she died.
Hopp and Poeppelmeyer, who recently forged a friendship out of their shared trauma, plan to be together as the first memorial to those who died is dedicated Saturday, the 70th anniversary of the bombing.
Until now, the fate of the victims has been overshadowed by the dramatic details of the bombing, the glaring absence of a federal law against attacking a plane and the meticulous investigation into what happened.
“We’ve had 70 years without having any respect at all for the victims who were lost,” Hopp said. “So it’s really nice to have this attention now.”
The United Airlines flight took off a few minutes late after a layover in Denver on its way to Portland. Oregon. Most of the passengers were from somewhere else, said Michael Hesse, the president of the Denver Police Museum who spearheaded the effort to create a memorial at the air traffic control tower of the city’s former airport, which is now part of a brew pub.
That’s part of the reason no memorial was ever built before, Hesse suggested. The granite slab with victims’ names listed within the outline of a plane will also include the seals of local and federal law enforcement agencies who responded to the bombing.
A separate memorial at the crash site, where homes are now being built, is also in the works.
The blast, a wake-up call to the danger posed to the emerging airline industry, wasn’t terrorism but the result of a personal grudge. Jack Gilbert Graham confessed to putting 25 sticks of dynamite attached to a timer into the luggage of his mother, who had put him in an orphanage as a boy. He bought a travel life insurance policy in her name, apparently at a vending machine at the airport, said historian Jeremy Morton, who developed an exhibit on the bombing at the History Colorado Center.
Graham planned to cover his tracks by having the plane explode over the mountains in Wyoming, making it difficult to investigate the crash, Morton said. But the flight’s delay caused the plane to explode over beet fields north of the city, allowing investigators to piece together the wreckage and interview eyewitnesses.
At the time, federal law outlawed attacks on trains and ships but not airplanes, leading Graham to be swiftly prosecuted in state court for a single count of premeditated murder for killing his mother, Daisie King. None of the others who died were named as victims.
Congress outlawed attacks on airplanes shortly after Graham was convicted. Graham, who was married with two young children, was executed in January 1957.
FBI records show Graham may not have been the first saboteur of an airliner: High explosives were strongly suspected in the 1933 crash of a United airliner over Indiana that killed seven people, but experts held out the possibility it was caused by exploding gas vapors.
The FBI said its probe of the Colorado crash provided a template to guide future complex airline investigations, including the terrorist bombing of a Pan Am jumbo jet over Lockerbie, Scotland, in 1988. That attack, using a bomb hidden in a cassette recorder packed inside a checked suitcase, led to the strengthening of baggage screening procedures, said Jeff Davis, senior fellow at the Eno Center for Transportation.
After the bombing, Hopp joined his family and his girlfriend — who would later become his wife — to help find and protect bodies from looters until others could take them to a makeshift morgue. Hopp’s father later broke down recounting what had happened and the family developed an unspoken agreement not to discuss the bombing. For years, Hopp said he woke up after having bad dreams about bodies.
Poeppelmeyer was 42 when she first heard the story about how her mother reacted to her father’s death. Her mother’s second husband was jealous and forbid anyone from speaking about the father she was named after, Marion Pierce Hobgood, while she was growing up, she said. An intense period of emotional and spiritual healing after a series of hardships as an adult led her to want to learn more about her father and she eventually published a book, “Finding My Father,” in 2019 about her quest.
She thought about reaching out to Hopp, believed to be one of the few remaining volunteers who helped recover bodies, but was reluctant because she did not want to force him to revisit that time. But she decided to contact him in 2022 after a mutual contact told her the crash site was being developed.
After meeting Poeppelmeyer and hearing her story, Hopp said his focus began to shift from those who died to those left behind and still suffering because of the bombing. He called Poeppelmeyer “a blessing.”
“There’s just a bond there, a beautiful bond because we have this shared story, the two sides of the coin,” she said.
Each time they talk, Poeppelmeyer says Hopp will share more information about what happened. She recently learned that most of the bodies were found on the Hopp family’s farm, including one close to their house.
She knows there were hundreds of people out helping after the crash. But she thinks it could have been Hopp who found her father after the crash.
“I just like to think that perhaps he did,” she said.
