Every day around 2 p.m. Maurice Gibb would drop into one of his two favorite Miami diners—Jimmy's East Side or the Stadium—and order eggs. On Jan. 8 it was the Stadium. Before his omelette arrived, "he complained about having indigestion," says his pal Frederic Renucci. "He was uncomfortable, but he ate."

When he got home to his Miami Beach mansion, just three miles from the homes of brothers—and fellow Bee Gees—Barry and Robin, Maurice doubled over in pain. At 5:30 p.m. his son Adam dialed 911; minutes later medics rushed the 53-year-old musician to Mount Sinai Medical Center. What happened next is unclear. According to his brothers, Gibb suffered a heart attack at around 4 a.m. and underwent abdominal surgery four hours later. "The fact that they had to operate during the shock of a cardiac arrest is very questionable," a distraught Barry was quoted in a British newspaper. "We believe negligence occurred."

A Mount Sinai spokesperson, citing privacy laws, declined to comment, but Barry and Robin said that surgeons had found Maurice's intestines twisted, possibly the result of a birth defect, and removed 80 percent of them. As his postoperative prognosis worsened, Maurice's wife, Yvonne, 52, Adam, 26, and daughter Samantha, 22, kept a bedside vigil. His death, at 12:10 a.m. on Sunday, Jan. 12, "has just destroyed them," said Barry. "Mo was their world."

In the music world Maurice was known as the funny Bee Gee, a wise-cracker who, said Barry, "liked being silly. He would never walk into a room. He would prance." Playing electric bass, guitar and keyboard, as well as singing backup vocals, he was "the most musically versatile" of the trio, says former Bee Gees sound engineer Dennis Hetzendorfer. The group sold more than 110 million records over four decades, most famously the Saturday Night Fever soundtrack that defined disco. But even after an anti-Bee Gees backlash in the '80s, Maurice was unperturbed. "It only infringes on our fun if we start to believe everything people say," he told PEOPLE in 2001.

The fun began in Manchester, England, with "three kids who wanted to be like the Beatles," the musician recalled. In 1958, when twins Robin and Maurice were 8, their parents, Hugh, a dance band leader, and Barbara, a singer, moved the family to Australia, where the brothers first performed as the Bee Gees (named, in part, for Bill Gates, a then-influential deejay). By 1964 they were known as Australia's Beatles, and their fame soon spread to U.K. and the U.S. But with success came excess—at least for Maurice. He acquired cars, mansions and a drinking problem that he said "helped break up my first marriage," to British pop star Lulu, in 1973. He and Yvonne Spencely, a steakhouse manager, wed in 1975.

Maurice's efforts to stay sober were hampered when youngest brother Andy, a cocaine user, died in 1988 of a heart ailment at 30; Maurice consoled himself with booze. Terrified after a 1991 binge during which he threatened Yvonne and the kids with a gun, he joined AA and became dedicated to his sobriety. Still, he kept up a smoking habit even as he raced around the woods on weekends as a paintball enthusiast. "My big sport," he called it. And, indeed, he was all set to play an upcoming tournament when he fell ill. His family is still incredulous that he's gone—and determined to find out exactly what happened. "We will pursue every factor of the final hours of Maurice's life," said Barry. "That will be our quest from now on."

Michael A. Lipton
Don Sider and Linda Trischitta in Miami Beach and Pete Norman in London