The $7 billion penalty that CitiGroup agreed to pay was based upon evidence that it sold mortgage backed securities to customers despite the knowledge that investors would suffer large losses. The agreement reached with CitiGroup does not prevent the government from pursuing criminal charges against individuals or the bank. However, the Justice Department has seldom prosecuted banks on criminal charges. Essentially, it would put banks out of business.
The government may also decided to prosecute Bank Of America on similar charges. BOA is fighting against prosecution on the grounds that it should not be liable for the behavior of Merrill Lynch which sold toxic mortgage securities to investors prior to its acquisition by BOA. It purchased Merrill under pressure from the government which wanted to avoid a dangerous bankruptcy.