She began making movies for Universal Pictures in 1913 with her first feature being A Prisoner in the Harem. She was known as Countess Rosita Marstini. In 1916, she debuted at the Pantages Theater in Los Angeles, California in Woman"s Wits, a play by Will Wyatt.
She played the Pantages" circuit for an additional eight months.
Mission Marstini was mentioned in news items after the body of Harry I. Katz was discovered at the door of his luxurious apartment in Los Angeles on November 10, 1924. Katz was a wealthy musician and society figure who was murdered by gunshot.
Rosita was traced to him by notes she had written which were discovered in the dead man"s residence. In one communication she referred to herself as that bad woman Rosita.
Reports by newspapers revealed that Marstini was engaged to Katz.
She claimed to have not seen him for a week. The victim was known to carry large amounts of money and may have been in possession of the Crown jewels of Russia. The gems disappeared following the assassinations of Czar Nicholas II and his family.
Aside from jewels, Katz was thought to have been wealthy from large profits in real estate and sales of liquor.
Police surmised that his murder was the act of an underworld figure who was seeking revenge. Prior to her death Rosita resided in Los Angeles for 33 years.
She died in 1948 at the age of 54. Her funeral was conducted in Pierce Brothers Hollywood Chapel.