WASHINGTON — For months, commentators and officials describing special counsel Robert Mueller's investigation into ties between the Trump campaign and Russia have used words such as "collusion" and "coordination" to summarize the complicated federal probe.
President Donald Trump himself has latched onto the terms, declaring on Twitter last week that there had been "NO COLLUSION" after criminal charges were unveiled against three of his ex-campaign aides.
But the words by themselves do little to explain how campaign officials might be prosecuted for contacts with Russian operatives, according to legal experts. That raises questions about which crimes Mueller's prosecutors will use to bring criminal cases stemming from what began as a FBI counterintelligence investigation 15 months ago.
"Conspiracy itself is not a crime: You've got to conspire to commit a crime," said Kate Stith, a former federal prosecutor and professor at Yale Law School. "The question is, what crimes are they looking at?"
WHAT CHARGES HAVE BEEN FILED?
That question was partially answered when a judge unsealed an indictment against onetime Trump campaign chairman Paul Manafort and his deputy, Rick Gates, who were charged with violating federal money laundering, foreign lobbying and banking laws for behavior occurring as far back as 2012.
Both men have pleaded not guilty. The court documents make no mention of contacts with Russians during the presidential campaign.
Mueller had the authority to bring the case since his mission is to investigate any "links and/or coordination between the Russian government and individuals associated with the campaign of President Donald Trump," plus any matters that arise from that inquiry, according to a May letter from the deputy attorney general.
But how Mueller's prosecutors will handle other Trump campaign aides who have had contact with Russians — an act that, by itself, doesn't necessarily constitute a crime — remains only partially answered.
George Papadopoulos, a foreign policy aide who according to court papers discussed with Russians Hillary Clinton's emails and the possibility of a meeting between Trump and Russian President Vladimir Putin, was charged with lying to FBI agents about his contacts, not the contacts themselves.
Papadopoulos pleaded guilty and is cooperating with investigators.
"Talking to foreign officials is not by itself a crime. Investing in foreign ventures including Russian ventures is not a crime," said Joel Brenner, a former top lawyer at the NSA and DNI. "Mueller, in order to prove a conspiracy involving any such activities, would have to show that the activities were part of something criminal such as trading changes in public policy for commercial benefits."
WHAT ABOUT ELECTION MEDDLING?
Mueller's probe into connections between Trump's campaign and Russia comes against the backdrop of a much broader Russian effort to interfere in the 2016 U.S. presidential election, more evidence of which was disclosed publicly last week.
The Associated Press reported that the Russian hacking effort that targeted Hillary Clinton's campaign chairman was part of a much broader hacking campaign; and congressional testimony by lawyers for social media companies revealed that millions of Americans viewed politically divisive ads pumped into their social media feeds by the Russians.
Counterintelligence officers investigating the case must determine whether any aspect of that influence effort was coordinated or facilitated via campaign officials, experts said.
Frank Montoya, a former top FBI counterintelligence agent, said Mueller investigators working simultaneously on criminal and counterintelligence probes are likely exchanging notes as they look for signs of a two-way conspiracy to break laws such as those statutes covering campaign finance, fraud, theft or financial dealings.
"Conspiracy is going to be a big part of the investigative lines because that's how you tie everybody together," he said.