A letter sent to the attorney for White House advisor Jared Kushner by the leaders of the Senate Judiciary Committee on Thursday suggests Michael Flynn could be the next Trump associate to be prosecuted, a former Whitewater prosecutor told CNBC.
In addition to "all communications to, from, or copied" to Flynn, former national security advisor, since Election Day, the senators requested that Kushner's attorney search for more than two dozen specific terms in communications between the two men, including Putin, sanctions and Kislyak, referring to the then-Russian Ambassador Sergey Kislyak.
"I think it indicates that Flynn is next," Robert Ray, former independent counsel for the Whitewater investigation, told CNBC.
The letter, signed by Sen. Chuck Grassley, R-Iowa, as well as Sen. Dianne Feinstein, D-Calif., suggested that the committee is looking into multiple reports of wrongdoing connected to Flynn's role in the 2016 presidential campaign.
The terms offer insights into the scope of the Senate Judiciary Committee investigation into alleged collusion between the Trump campaign and Russia.
Examining search terms "gives you a certain hint" about what investigators are probing, Sol Wisenberg, who served as deputy independent counsel in the Whitewater investigation, said in a phone interview.
For instance, the senators requested Kushner's attorney search for the terms "Peter Smith," "WikiLeaks," "Clinton," and "hacking" in communications between Kushner and Flynn.
In August, The Wall Street Journal reported that special counsel Robert Mueller was examining whether Flynn played a role in obtaining Hillary Clinton's emails from Russian hackers. That effort was reportedly led by Republican activist Peter Smith.
The senators also requested search terms related to the U.S. sanctions on Russian businesses that have played an important role in the ongoing investigations by federal and congressional officials.
They asked for communications including the name of a Russian bank that was sanctioned by the United States, Vnesheconombank, or VEB.
The chief of that bank met with Kushner, the president's son-in-law, in New York in December 2016, just a few weeks before Flynn discussed sanctions with the then-Russian ambassador. Earlier that month, Flynn and Kushner had met the ambassador at Trump Tower in New York and reportedly discussed a secret channel between the Trump transition team and Moscow.
The senators also requested documents containing the name "Erik Prince" and "Seychelles," suggesting the investigators are interested in a reported secret meeting said to involve Blackwater founder Erik Prince.
The meeting, held in the Seychelles islands in the Indian ocean nine days before the inauguration, reportedly involved establishing a backchannel between the Russian government and the Trump team. A Prince spokesman told The Washington Post its report was a "complete fabrication."
Kushner, whose lawyer did not respond to a request for comment from CNBC, said in a July letter to Congress that he "had no discussion about the sanctions" during the meeting with the banker. He also denied discussing a secret back channel with the Russians.
In a letter sent to the congressional committee, Kushner's attorney thanked the committee for clarifying what documents it was seeking.
Congressional committees are conducting investigations that are separate from Mueller's. Unlike Mueller, the congressional committees are unable to bring charges, Wisenberg said. The special counsel has declined to comment on its interactions with congressional investigators.
If charges were brought against Flynn, who resigned as Trump's national security advisor after only 24 days, he would be the first Trump administration official to be officially accused of criminal wrongdoing in connection with the probes into foreign meddling in the 2016 election.
In October, the special counsel indicted two campaign officials, Paul Manafort and Richard Gates. A third, George Papadopoulos, pleaded guilty to making false statements to the FBI.
WATCH: WSJ report raises big questions about Flynn & Russian hackers
