ALBQUERQUE, N.M. >> Ted Williams is the last major league baseball player to hit over .400. The Boston Red Sox slugger captivated millions with his dazzling swing and towering homers throughout the 1940s and 1950s in competition with New York Yankees hero Joe DiMaggio.

But beneath the smiles and happy trots around the bases sat a man consumed with rage. For years, the baseball legend would shun his ethnic heritage and kept his family’s past a secret. Only when he’d begin to speak out on behalf of black players would he begin to slowly reveal his connections to his Mexican-American Southern California family and the experiences that shaped him.

A new PBS “American Masters” documentary explores the life of Williams and his volatile relationships with his family and the press. The upcoming film uses rare footage and family interviews to paint a picture of an entangled figure who hid his past while enjoying the admiration of adoring fans. It includes unreleased color footage of Williams’ final game that was shot by a fan.

Williams, often called the “greatest hitter who ever lived,” was followed closely by sports writers thanks to his superb slugging skills and John Wayne-like persona as a foul-mouth outdoorsman. But the future Hall of Famer regularly clashed with critical journalists and had public spats with his numerous wives. The slugger also lost prime years because of service in World War II and the Korean War — something that angered him.

“We wanted to know…who was this man, who had such an effect on so many people?” director Nick Davis said. “He was so complicated and so full of contradictions and rages. Where did it all come from?”

The San Diego-born Williams played 19 years as a left fielder for the Boston Red Sox where he won two American League Most Valuable Player Awards and twice took the Triple Crown. He finished his career with a .344 batting average and 521 home runs, both of which rank among the top in baseball history.

While many of Williams’ professional accomplishments and personal clashes were widely known, Davis said few knew about Williams’ ethnic background until Ben Bradlee, Jr.’s well-researched 2013 book, “The Kid: The Immortal Life of Ted Williams.”

Davis said Williams kept his Mexican-American heritage a secret at a time when no black players were allowed in the major leagues and the Red Sox were owned by Tom Yawkey, a controversial figure who was the last owner to integrate a major league baseball team.

Williams was born to Samuel Stuart Williams, a white photographer and pickle salesman, and May Venzor, a Mexican-American Salvation Army devotee who often volunteered in Tijuana, Mexico, leaving Williams and his brother to fend for themselves with their alcoholic father, Bradlee said. His Mexican family ended up in San Diego as tension simmered before the Mexican Revolution began in 1910.

It’s a past Williams concealed until near the end of his life, said Bradlee. “He was ashamed.”

After his sensational 1939 rookie year, Williams returned to San Diego to find around 20 of his Mexican-Americans relatives waiting for him at the train station. Williams took one look at them and fled.

Bradlee, who was among those interviewed for the film and who found some of Williams’ cousins, said the family remained proud of his on-the-field achievements.

“But you can see they were a little bit hurt that he had shunned them,” Bradlee said.

In the film, daughter Claudia Williams said she would sometimes ask her father about his mother. But he refused to talk about her, or his past, she said.

Williams was inducted into the Baseball Hall of Fame as soon as he became eligible. Williams wanted to use his speech to call for the Hall of Fame to recognize players of the Negro Leagues who had been excluded solely based on their skin color. Friends would say Williams, despite his own ambivalence about his own background, remembered the discrimination Mexican Americans faced in California.

But baseball officials wanted Williams to drop the reference. “You don’t tell Ted Williams what he can and cannot do,” Claudia Williams said in the film.

Williams gave his Hall of Fame speech his way, and soon after, players of the Negro Leagues were inducted into the Hall of Fame.

American Masters “Ted Williams: ‘The Greatest Hitter Who Ever Lived’” airs on most PBS stations on Monday.