From "Manson The Life and Times of Charles Manson"
Page 433 -
"I had hoped to interview Beausoleil, but learned that he had agreed with film maker Steven Martin to decline all interviews while they cooperated on a documentary about his life."
Page 474 Bibliography -
"Steven M. Martin grew up in Los Angeles. His Theremin: An Electronic Odyssey won the Documentary Filmaker's Trophy at the 1994 Sundance Film Festival. He is currently working on a film about Bobby Beausoleil."
Theremin: An Electronic Odyssey(1994)
A documentary about the inventor of the first electronic synthesiser instrument and his subsequent life after he was abducted by the KGB as well as a history of his instrument.
Brian Wilson was also in this documentary (Theremin)... apparently this instrument was used in Good Vibratations.
Mr. Martin was also an actor appearing in: The Addams Family, Addams Family Values, Fast Times At Ridgemont High (one of the angry twins - his twin brother is actor Douglas Martin), and Hudson Hawk...
The Martin twins in Fast Times at Ridgemont High