The US authorities charged two former Russian FSB agents and two hackers for 2014 Yahoo data breach that caused the exposure of 500 Million Yahoo accounts. The four defendants are: Dmitry Dokuchaev, Igor Anatolyevich Sushchin, aka Magg, 29 a Russian national and resident, who has been on the FBIs Most Wanted Hackers list. The hackers accessed at least 30 million accounts as part of a spam campaign aimed to steal the email contents of thousands of people.”]
Source: http://securityaffairs.co/wordpress/57171/cyber-crime/2014-yahoo-data-breach.html