Martin Shkreli sued the former chief executive officer of Retrophin Inc. and two other executives for at least $30 million, claiming they “unceremoniously and illegally” ousted him from the company in 2014 for their own benefit.

Shkreli, 36, was sentenced to seven years in prison last year for stealing $11 million to repay investors after the hedge-fund-manager-turned-drug-executive, lost money on risky trades. He sued Stephen Aselage, Retrophin’s former CEO and currently a director, and two other executives in New York...