Updated at 7:58 p.m. ET
Newly discovered emails being examined by the FBI in relation to Hillary Clinton's email server came to light in the course of an unrelated criminal investigation of Anthony Weiner, a source familiar with the matter tells NPR's Carrie Johnson.
Weiner is the estranged husband of close Clinton aide Huma Abedin; he has been under scrutiny for sending illicit text messages to an underage girl. Sources said authorities seized electronic devices in their home, which led them to this new information.