On September 3, the music world was shocked to learn of the passing of Steely Dan co-founder Walter Becker. Today, Rolling Stone has shared a letter penned by Becker’s widow, Delia, explaining the circumstances behind Walter’s death.

Delia revealed Walter died of “an extremely aggressive form of esophageal cancer.” Becker was diagnosed with the illness four months before his passing and it spread extremely quickly. “The cancer was detected during one of his annual medical checkups and its presence came as a grim surprise to Walter, his doctors and to me. It seemed to have come out of nowhere and had spread with terrifying speed,” Delia wrote.

“Walter chose an intense regimen of chemotherapy at Sloan Kettering though, between the cancer’s aggressiveness and the overwhelming toxicity resulting from the chemotherapy treatments, Walter died less than four months after the cancer was detected,” Delia wrote. “Walter passed peacefully in our New York City home, surrounded by his family, his music, and a blustery rainstorm — one of his favorite sounds — blowing outside the window. In keeping with his wishes, he was cremated without ceremony or memorial in New York City,” read part of the note.

Walter aimed to keep his privacy and didn’t share word of his condition with fans. He expected to return to the stage, but “he just ran out of time much sooner than any of us thought possible” as per Delia. Mrs. Becker was deeply moved by the tributes that poured in following Walter’s death. “Even his ‘Number 1 Fan’ — me — would not have predicted anything close to the depth and breadth of public expressions from those whose lives were enriched by Walter — by his talent, his kindness, and his skill at inspiring some wicked fun.”

Head to Rolling Stone for the full text of Delia’s letter.

Watch one of Walter’s last “Hey Nineteen” raps thanks to CalVid: