Beck was found on Saturday by police officers responding to a call to his home in suburban Phoenix, police department spokesman Andy Hill said on Sunday. Foul play is not suspected.
With long hair framing a menacing stare and an aggressive arm swing before delivering a pitch, the outgoing right-hander was a memorable personality and a three-time All-Star who twice led the National League in saves. He spent the first seven of his 13 major league season with the San Francisco Giants.
Beck was popular with his teammates, reporters and fans, but battled personal demons late in his life. He abruptly left the San Diego Padres for a two-month stint in drug rehabilitation during his final season in 2004.
"He was having some problems, and I just knew he went into rehab and joined us later that year," said Giants manager Bruce Bochy, the Padres' manager at the time. "It's so sad when you see healthy players go at such a young age. This is a bad day in baseball to lose a guy who did so much for the game."
Nicknamed "Shooter," Beck played for the Giants (1991-97), the Chicago Cubs (1998-99) and the Boston Red Sox (1999-2001) before finishing his career with the Padres (2003-04).
Beck led the majors in saves in 1993, when he set the Giants' single-season record with 48. He was San Francisco's career saves leader with 199 until Robb Nen passed him in 2002.
Beck led the majors again in 1998 with 51 saves for Chicago, helping the Cubs win the NL wild card. He had a career record of 38-45 in 704 games, with a 3.30 ERA.
Beck is survived by his wife, Stacey, and two children.