Thus far, the investigation explored how the identities and communications of the Trump transition team were collected by U.S. intelligence agencies and then revealed to, and disseminated among high-ranking members of the Obama administration.
House Intelligence Committee Chairman Devin Nunes (R-CA) plans to audit files from the National Security Agency (NSA) and White House to discover whether conversations and identities of presidential candidates, or members of Congress, were also swept up during NSA's surveillance of foreign leaders.
Nunes also will review whether the Obama National Security Council and White House counsel collected and distributed the information for reasons unrelated to foreign intelligence (and probably for political reasons).
"We will be performing an accounting of all unmasking for political purposes focused on the previous White House administration," one committee member told Fox News. "This is now a full-blown investigation."
Senate committee staffers have also broadened their investigation to determine whether presidential candidates were unmasked and information was misused. It is a felony to unmask the names of American citizens. They also want to find out what role Susan Rice, among others, played following reports that she requested Trump-affiliated names be unmasked.
For a private American citizen to be 'unmasked' in an intelligence report is quite rare and usually done only if it has some foreign intelligence value. Thus, it is typically done if the American is a suspect in a crime, is in personal danger, or has to be named to explain the context of the intelligence report.
If it is found that Rice unmasked those names and leaked them to the media, she should, but likely will not, go to prison. (For more on this reasoning, see Hillary Clinton and Benghazi.)