He was born in Gävle, Sweden, and taught himself how to compose, although he later studied at the University of Uppsala. He sang in the chorus Bel Canto, was active as a jazz musician, and worked as a producer for Swedish Radio. He was known for his avant-gardist, post-Webernian composition Pentagram for string quartet that won first prize at the Gaudeamus Festival in Bilthovenin 1960. He became known for his vocal and choral music, as well as his operas, such as Drömmen om Thérèse.
He is also remembered for writing two scores for films of Ingmar Bergman, Persona and Hour of the Wolf.
source: YouTube