U.S. President Joe Biden said that the United States was not sure where Russian mercenary Yevgeny Prigozhin was but quipped that he could be poisoned. "If I were he, I’d be careful what I ate," Biden said during a press conference in Helsinki. Prigozhin, chief of Russia's most-feared mercenary group, has not been seen in public since leaving Russia on June 24 after calling off a brief armed mutiny against Kremlin. Watch this video for more details