Bård Guldvik Eithun, also known as Faust, was born on April 21, 1974, in Hedmark, Norway. He had a passion for music from a young age. When he was sixteen, he moved to Lillehammer. There, he became the drummer for a band called Thorns, which was initially known as Stigma Diabolicum.

In the early 1990s, Eithun took his interests further by publishing an underground fanzine named Orcustus. This fanzine showcased his dedication to the music scene. In 1992, he moved to Oslo. In Oslo, he began working at a music shop called Helvete, owned by Øystein "Euronymous" Aarseth, a guitarist from the band Mayhem. Eithun had been pen-pals with Aarseth since 1987.

That same year, Eithun joined a well-known black metal band called Emperor as their drummer. This allowed him to become part of the early Norwegian black metal scene, where he gained recognition and built relationships with other musicians.

On August 21, 1992, Bård Guldvik Eithun, also known as Faust, stabbed Magne Andreassen to death in Lillehammer, Norway. The incident occurred after Andreassen approached Eithun in a drunken state and solicited him for sex while walking home from a pub. Eithun agreed to go with him to a secluded area in the woods, where he attacked Andreassen. He stabbed him 37 times and also stomped on his head multiple times.

After returning to Oslo the next day, Eithun confessed to other members of the black metal scene, including Aarseth and Varg Vikernes, about what he had done. Subsequently, Eithun, Aarseth, and Vikernes were involved in the arson of Holmenkollen Chapel. In August 1993, after Vikernes murdered Aarseth, Eithun was arrested. He confessed to the murder of Andreassen, claiming it was an impulsive act.

In early 1994, Eithun was convicted and sentenced to 14 years in prison. He served his time at Ullersmo prison and was released in 2003 for good behavior after spending nine years and four months behind bars. During his time in prison, he completed two bachelor degrees from the University of Oslo and later expressed remorse for his actions, calling them senseless.