Washington (CNN) Sen. Susan Collins sent a written note early Wednesday morning during President Donald Trump's impeachment trial minutes before Chief Justice John Roberts admonished both legal teams, a source with knowledge of the event tells CNN.

It is unclear if the note from Collins, a Maine Republican, led directly to Roberts' comments, or had specific language for him, but the note came shortly before the chief justice spoke. The note was sent as House Judiciary Chairman Jerry Nadler, a Democrat from New York, spoke and appeared to accuse senators of a "cover-up."

Senate Parliamentarian Elizabeth MacDonough was seen on TV cameras speaking to Roberts at 12:48 a.m. ET. It is not clear what the conversation between the two was about, but Roberts addressed the Senate at 12:55 a.m.

There were also heated language from one of the President's attorneys, Pat Cipollone, in the preceding 30 minutes, and Roberts specifically addressed both legal teams in his remarks.

Sen. Susan Collins of Maine, at right, walks with Sen. Dan Sullivan of Alaska to the Senate chamber at the Capitol on Wednesday.

"I think it is appropriate at this point for me to admonish both the House managers and the President's counsel, in equal terms, to remember that they are addressing the world's greatest deliberative body," Roberts said, appearing to refer to notes on the dais.

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