He moved to Hollywood, California, in his 20s and began investing in the production of a handful of films, including William Peter Blatty's The Exorcist.

The cast and crew worked with real big cats, leading to 70 people being injured during the making of the film.

[5] As director, Marshall wrote, co-produced, and starred in the film Roar (1981), which revolved around big cats and featured actress Tippi Hedren, his stepdaughter Melanie Griffith, and his sons, John and Jerry.

Both Marshall and Hedren saw a game warden's house in Zimbabwe overrun by lions, and learned about awareness for endangered animal and big cat species.

[4] Marshall and Hedren approached animal trainers for support on the training of numerous big cats, and were told the idea was impossible, dismissing them both as "brainsick" and "completely and utterly insane" to allow big cats on-set without at least two experienced trainers for each animal.

[10] During that time, Marshall and his family began housing lions first at his Sherman Oaks home, a property he bought in Santa Clarita, and later in Acton, California.

[14] Other accidents included a flood from a broken dam, a fire, destroyed equipment, financial issues, and a feline virus which plagued most of the big cats.

This resulted in their four houses being sold in order to pay the debt, and the entire production crew was fired to compensate for the losses.

[11] Marshall and Hedren decided to continue the production and rebuilt the sets that had been destroyed, and hired many different crew members to finish the film.

The rights for the film, called Frances, were sold by Yates to Brooksfilms, the production company of Mel Brooks.

[23] Marshall was labeled "intense" by John, as he would often get angry on-set of the film and would shout at the cast, crew, and animal handlers when a take was ruined.