It’s a mystery that’s lasted for 50 years and lingers still: What happened on the summer night in 1969 when a car driven by Sen. Ted Kennedy plunged off the Dike Bridge into the waters off of Martha’s Vineyard, killing his 28-year-old passenger, Mary Jo Kopechne?
On July 18, 1969, Kopechne, who had worked on Sen. Robert F. Kennedy’s 1968 presidential bid, attended a reunion party with five of her fellow campaign workers, known as the “Boiler Room girls,” so named for their windowless office.
The party, held at a rental cottage on the island of Chappaquiddick in Massachusetts, was also attended by Ted, Robert’s younger brother, along with five other men, some of whom had also worked on the campaign.
What happened next that night remains unclear, even decades later. And many believe the scandal — beginning with Ted’s 10-hour delay in reporting the deadly accident as well as the lack of an autopsy and his evasiveness about answering the most basic questions about the events surrounding Kopechne’s death — kept him from reaching the White House.
A friend who worked on his 1980 presidential campaign told PEOPLE this of Chappaquiddick: “It hung over him like a permanent cloud. It’s the question everywhere all the time. He knew that.”
In his 2009 memoir, True Compass, Ted wrote: “That night on Chappaquiddick Island ended in a horrible tragedy that haunts me every day of my life. I had suffered sudden and violent loss far too many times, but this night was different. This night I was responsible. … Yes, it was an accident. But that doesn’t erase the fact that I had caused an innocent woman’s death.”
Of what happened that night, he once said: “There is not going to be any new information that will challenge my testimony.”
Not so: In the course of more than 60 interviews while reporting the Cover-Up podcast, PEOPLE learned otherwise.
For example, as revealed in the series’ seventh episode, Kopechne’s surviving family received a letter in 2018 labeled “The Untold Story of Chappaquiddick.”
In it, the writer (who declined to be interviewed by PEOPLE) described a lunch he had had years earlier with his wife and her friend, a woman who had attended the party the night Mary Jo died. The woman was referred to by a pseudonym, “Betty,” to protect her identity.
The man’s letter described how Kopechne had had too much to drink that night in 1969 and did not feel well. Betty put her in the back seat of the senator’s car to rest and then she returned to the cottage where she, too, fell asleep.
According to the letter, in the hours that followed Ted and another female party guest went for a drive in his car, unaware that Kopechne was in the back. When the car went over the bridge, Ted and his passenger escaped and returned to the party — unaware of who they left behind.
The letter went on to say that when Betty woke up the next morning, she was told Ted’s car had crashed and she asked about Kopechne. To her surprise, no one had been aware of Kopechne’s presence in the vehicle.
Once Betty relayed her story, according to the letter, “…the Kennedy damage control machine kicked in and informed the shocked senator.”
It was only that next morning, after the upside-down car had been spied in Poucha Pond by two fishermen, that Ted went to the local police station to report the accident. (A spokesperson for Ted’s widow, Victoria Reggie, declined to comment on the letter last year.)
Although it was ruled that Mary Jo died by drowning, there were always lingering questions about exactly how long she survived in the car. Ted was ultimately charged with leaving the scene of an accident, to which he pleaded guilty, receiving a two-month suspended sentence.
A year after receiving the letter, Kopechne’s cousin Georgetta Potoski, now 79, still wonders if it’s the full story.
“I’m not convinced the mystery has been solved,” she tells PEOPLE. “I know there are things that we do not know about what happened that night. The truth, even if it’s not what you want to hear, at least has some dignity around it.”
“There was such a cover-up and such disregard for Mary Jo when she died,” Potoski says. “I don’t think there will ever be justice for the loss of her life. [But] I think the truth would make our hearts rest easier.”
Kopechne would have been 79 this year. “She could have had a wonderful life,” Potoski says.
“Maybe she would be a grandmother,” Potoski continues. “It would have been wonderful to have her in my life.”
But Potoski and her son, William Nelson, are heartened by the renewed interest in Kopechne over the past year.
“We feel Mary Jo is finally seen as the intelligent and lovely young woman she was,” says Potoski. “Finally, she’s no longer described as ‘the girl who died in the car.’ And our scholarship fund in her name at Misericordia University is coming along. We’ve granted two scholarships, and that’s brought happiness to us.”
Says Nelson: “The first thing was to correct history in how people saw Mary Jo and to portray her accurately. With the book we wrote, Our Mary Jo and the podcast, now her memory and her character are more truthfully represented. Our second goal is to fund the scholarship in her name, so that her life continues to have an impact.”
The family hopes that, finally, any remaining silence around the case is shattered.
“The more we hear from people, the more people help us add pieces to the puzzle,” Nelson says, “and that will hopefully spur on others to share what happened. We still have questions, but we have come a long way.”
For more on the Chappaquiddick scandal, listen to PEOPLE’s podcast Cover-Up on Apple Podcasts, Spotify, Google Play or wherever podcasts are available. And to continue the discussion, join our Facebook group to share your thoughts and theories or reach us directly at email@example.com.