Spector was "pronounced deceased of natural causes at 6:35 p.m. on Saturday, January 16, 2021, at an outside hospital. His official cause of death will be determined by the medical examiner in the San Joaquin County Sheriff's Office," the California Department of Corrections and Rehabilitation said in a statement Sunday.
"Before his incarceration, Spector was an influential record producer, musician and songwriter best known for developing a music production technique called the 'wall of sound,'' the prison said in the release.
TMZ said he died from COVID-related complications four weeks after he was diagnosed.
Spector was found guilty of second-degree murder by a Los Angeles jury after his second trial in 2009. He was sentenced to 19 years-to-life in prison.
The producer's first trial ended in a hung jury and was declared a mistrial in 2007.
Spector's lawyers argued Clarkson could have killed herself at Spector's home.
Among the hit songs Spector produced in the 1960s and '70s were "To Know Him is To Love Him" by the Teddy Bears, The Righteous Brothers' "You Lost that Lovin' Feeling," "Unchained Melody," "You're My Soul and Inspiration," The Ronettes' "Be My Baby," The Crystals' "He's a Rebel" and Ike & Tina Turner's "River Deep, Mountain High."
Spector also produced The Beatles' final album, "Let It Be," and John Lennon's solo songs "Instant Karma" and "Imagine."
The Grammy winner was inducted into the Rock and Roll Hall of Fame in 1989.
Al Pacino played him in the 2013 movie, Phil Spector.
Notable deaths of 2021