Republican Chairman Richard Burr and Democratic Vice Chairman Mark Warner also warned about the risk to future USA elections posed by Russian Federation, including what is expected to be a closely contested election next month for governor of Warner's home state, Virginia.
"Questions that you might have surrounding Comey's firing are better answered by the general counsel or by the Justice Department, not the Select Committee of Intelligence in the United States Senate", Burr continued.
"If you look from 10,000 feet", Senate Intelligence Committee Chairman Richard Burr told reporters at a briefing Wednesday, "the subject matter" of the 3,000 Russian-bought Facebook ads that have been turned over to his committee "seems to have been to create chaos in every group that they could possibly identify in America".
The committee is still investigating whether the Russians had any coordination with members of Trump's campaign, and he suggested that they were still examining just how Russians knew where to target social media spots.
Former MI6 officer Christopher Steele compiled the dossier, which Trump was told by former Federal Bureau of Investigation director James Comey contained salacious material about the businessman-turned-president. "The committee can not really decide the credibility of the dossier without understanding things like who paid for it, who are your sources and sub-sources", Burr added.
While Trump's defenders have dismissed the Steele dossier as a politically-motivated smear, Burr indicated that his committee is still working to evaluate its claims and has not dismissed it outright.
The senate intelligence leaders revealed that during the course of their investigations, they conducted over 100 interviews, reviewed 100,000 documents and have gone through over 4,000 transcripts.
Among those who have been questioned are former campaign chairman Paul Manafort, as well as Mr Trump's son-in-law and adviser Jared Kushner.
Republican Sen. Richard Burr of North Carolina and Democratic Sen. He said Russian hackers had also tested the vulnerabilities of election systems in 21 states, though there's no evidence that any voting tallies were altered.
While both Burr and Vice Chairman Sen.
Burr made it clear that his committee could not release the ads that Facebook handed over as part of the investigation but Facebook and the other companies are not constrained by the committee from doing so.
"The Russian intelligence service is determined and clever, and I recommend that every campaign and every election official take this very seriously", Burr said.
Facebook and Twitter said on Wednesday they'll send representatives to appear, Recode reported. The topics included a campaign event at the Mayflower Hotel when some Trump campaign officials met with then-Russian ambassador Sergey Kislak, the drafting of the Republican party campaign platform as it related to relations with Russia, and the memos taken by former Federal Bureau of Investigation director James Comey.
This story has been edited and will continue to update with additional developments.