Rod Beck, a relief pitcher who wore a bushy mustache while earning 286 career saves, was found dead Saturday. He was 38.

Beck was found by police officers responding to a call to his home in suburban Phoenix, according to police department spokesman Andy Hill. Foul play is not suspected, though the cause of death might not be known for several days.

With long hair framing a menacing stare and an aggressive arm swing before delivering a pitch, the outgoing right-hander was a memorable baseball personality and a three-time All-Star who twice led the NL in saves. He spent the first seven of his 13 major league seasons with the San Francisco Giants.

Beck was popular with his teammates, reporters, and fans, but he 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 reportedly was living in a camper behind the Iowa Cubs’ center-field fence when San Diego called.

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.

“He was a great teammate and a great competitor,” said Giants shortstop Rich Aurilia, who played his first three major league seasons with Beck in San Francisco. “He left an impression on everybody he played with. You talk to everybody, they’ll have nothing but good things to say. He’s somebody that Giants fans will always remember.”

Mr. Aurilia recalled being wary of Beck’s mustache and mullet when he came up as a rookie in 1995 — but Beck was among the first to congratulate Mr. Aurilia on making the team.

Beck was a favorite at Candlestick Park through most of the 1990s, but he left to sign with the Cubs as a free agent in 1998.

He saved 51 games in his first season in Chicago, but he managed just 46 saves in his final five seasons combined.