John Louis Loffredo was born in New York City. He initially planned to be a missionary, and began writing screenplays at the age of 14.[1]
In the early 1970s, he moved to Rome, and made his film acting debut in Vittorio De Sica's The Garden of the Finzi-Continis. He appeared in various films, notably several collaborations with Enzo G. Castellari and Roberto Rossellini. He was sometimes credited under the Italianized stage names Gianni Loffredo and Gianluigi Loffredo.[2]
Later in the decade, he moved to Austria.[1][2]
In 1978, he wrote and produced the film Just a Gigolo, starring David Bowie and Marlene Dietrich.[3] He contributed to the screenplay for Enzo G. Castellari's Spaghetti Western Keoma (1976),[5] Casanova & Co. (1977), and Judgment in Berlin (1988); and wrote The Golden Lady (1979).
In 1985, Sinclair published the historical novel Shaka Zulu, based on the life of the 19th-century Zulu King. The following year, the novel was adapted into a SABC miniseries of the same name in 1986.[1] In 2001, he wrote and directed a sequel telefilm, Shaka Zulu: The Citadel.
In 2018, he wrote and directed the film A Rose in Winter, a biopic of Edith Stein (Saint Teresa of the Cross).[6][7]
In the 1980s, Sinclair left acting to pursue a career in medicine. He graduated from the University of Virginia and Johns Hopkins University, as an M.D. with a specialization in tropical medicine. As a member of Médecins Sans Frontières, he worked at Grant Medical College in India (where he worked with Mother Teresa[7]) and Chris Hani Baragwanath Hospital in South Africa.[1]
