It’s nearly midnight in a nondescript condo complex a few blocks from Universal Studios in Orlando, and Tatiana Gruzdeva has been crying all day. Though neither of us knows it yet, as she sits on the corner of her bed and sobs in tiny convulsions, the fact that she’s talking to me will lead to her being arrested by federal agents, placed in solitary confinement, and deported back to Russia.

Next to us on the bed are nine teddy bears. Eight of them came with her from Tiraspol, Moldova. The ninth was a gift from her boyfriend, Ibragim Todashev. Today would have been Ibragim’s 28th birthday, but he is not here to see it, because in the early hours of May 22, 2013, a Boston FBI agent shot and killed him in this very apartment, under circumstances so strange that a Florida state prosecutor has opened an independent investigation. According to the FBI, just before Ibragim was shot—seven times, in two bursts, including once in the top of the head—he was about to write a confession implicating himself and alleged Boston Marathon bomber Tamerlan Tsarnaev in a brutal triple homicide that took place in Waltham, Massachusetts, in September 2011.

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It would take 18 months and two homemade bombs before FBI investigators exhumed the case—and once they did, they were able to move with uncanny speed. It took them mere hours to link Tamerlan to the Waltham triple homicide. The day after Tamerlan was killed in a shootout with Watertown police, plainclothes FBI agents detained his friend, Ibragim Todashev, at gunpoint. Although the FBI seems to have initially been looking for evidence of a wider terrorist cell in connection with the marathon bombings, within weeks its agents were questioning Ibragim about the Waltham murders. According to the FBI, agents were able to bring Ibragim to the brink of a written confession by pressuring him with circumstantial evidence.

If you believe the FBI’s account, then you must also believe this: If Waltham police had figured out who hacked three men to death on September 11, 2011, there’s a good chance we would not be talking about the Boston Marathon bombings. Tamerlan Tsarnaev and Ibragim Todashev might be alive and in jail. Dzhokhar Tsarnaev might be just another mop-headed, no-name stoner at UMass Dartmouth. There would be no One Fund. Krystle Campbell, Lu Lingzi, and Martin Richard would still be alive. Sean Collier would have graduated from the MIT police department to the Somerville Police Department by now. And for the friends and family of the three men who died in Waltham, perhaps their grief would not still be paired with such haunting questions.