TRURO, Mass. — Peter Manso, a writer and longtime Cape Cod resident known for his exhaustively researched books and articles, including biographies on the likes of Norman Mailer and Marlon Brando, has died. He was 80.

His wife, Anna Avellar, told the Cape Cod Times that Manso most likely died of a heart attack. He died Wednesday.

Manso conducted hundreds of interviews for his hefty biographies of Brando and Mailer, the newspaper reported. As a journalist, he profiled Arnold Schwarzenegger, Roy Cohn and other famous figures for publications like Playboy, Vanity Fair, The New York Times and Politico.

Manso was ensconced in the social and literary life of Provincetown for many years and closely followed the trial of Christa Worthington, a fashion writer who was killed in nearby Truro in 2002.

The book he wrote about the case, “Reasonable Doubt: The Fashion Writer, Cape Cod and the Trial of Chris McCowen” argued that McCowen, who is Black, did not get a fair trial because of his race and criticized the prosecutor, the newspaper reported at the time it was published. McCowen was sentenced to life in prison without parole.

Manso attended Antioch College and Johns Hopkins University and received his Ph.D. in English from the University of California, Berkeley, the newspaper reported.

Survivors include his brother, Victor; stepsons Chad and Anson Avellar; and grandchildren Kupala and Aaron Avellar.