The anonymous CIA whistleblower said that the Trump-Zelensky conversation, in which Trump repeatedly leaned on the Ukrainian president to have Joe Biden and his son Hunter investigated (implying that no military aid would be forthcoming otherwise) was only one of many such illegal conversations with foreign leaders.

White House staffers have been stashing the transcripts of these criminal interactions in a special electronic server used for highly classified documents.

The whistleblower also says that the reports of the Zelensky conversation were conveyed to him by several persons, who repeated the same details.

What this means is that there are numerous impeachable crimes and numerous potential whistleblowers who heard them occur or who have reliable reports of them.

via Witness Intimidation: Unbalanced Trump Seeks Whistleblower sources, hints Execution for Espionage