Nissan Motor Co. boss Carlos Ghosn built a parallel business as an investor in Silicon Valley with his son, using millions of dollars he received from an executive at a Nissan business partner in Oman.
The operation, known only to a handful of people, adds crucial new details to what is seen as the most serious criminal charge in a broad financial-crimes investigation against Mr. Ghosn. Japanese authorities arrested the former chief executive and chairman of Nissan at a Tokyo airport in November, following a monthslong…