Dec 17 (Reuters) - Pharmaceutical entrepreneur Martin Shkreli was arrested by the FBI on Thursday, amid a federal investigation related to his former hedge fund and a drug company he previously headed.

The previously disclosed investigation of Shkreli, 32, who is now chief executive of Turing Pharmaceuticals, stemmed from his time as manager of hedge fund MSMB Capital Management and chief executive of biopharmaceutical company Retrophin Inc .

His arrest, witnessed by Reuters, comes amid a continuing separate controversy that has turned Shkreli into a lightning rod for growing outrage over the soaring prices of prescription drugs. (Reporting by Nate Raymond; Editing by Ted Kerr)