David Crosby, the American guitarist and singer-songwriter, who was a founding member of both The Byrds and Crosby, Stills & Nash, has died, according to a statement on Thursday. He was 81.

A cause of death was not announced. Crosby reportedly had been battling a "long illness." He had been public about suffering from type 2 diabetes and was treated with insulin.

"It is with great sadness after a long illness, that our beloved David (Croz) Crosby has passed away. He was lovingly surrounded by his wife and soulmate Jan and son Django," his wife Jan Dance said in a statement to Variety.

"His legacy will continue to live on through his legendary music," the statement added.

Beach Boys legend Brian Wilson on Thursday posted a message on Twitter honoring Crosby.

Crosby was born in Los Angeles to an Academy Award-winning cinematographer father and a mother who worked as a salesperson at Macy's.

He joined the folk-rock band The Byrds in 1964.

He later became a part of the supergroup Crosby, Stills and Nash, which performed their first concert in 1969 at the Woodstock festival. The band would later add Neil Young.

The band's debut album, Deja Vu, sold 7 million copies.

Crosby was inducted into the Rock & Roll Hall of Fame twice. He was honored in 1991 with The Byrds and with Crosby, Stills & Nash in 1997.

Crosby had admitted to being addicted to alcohol, cocaine and heroin. In 1982, He was arrested on drug and weapons charges.

"My skin is like tissue paper, man. It tears or bruises. It's just part of being old," he said in an interview with the Guardian.

Music journalist Rob Tannenbaum shared former bandmate Graham Nash's statement about Crosby's death.