Chuck Cooper, the lawyer representing former national security adviser John Bolton, revealed an interesting detail in a letter to Congress last week.Cooper said Bolton "was personally involved in many of the events, meetings, and conversations about which you have already received testimony," but also meetings that have yet to be discussed.If he does testify, Bolton could be fatal to President Donald Trump's defense in the impeachment inquiry.Bolton has had more one-on-one interactions with Trump than any other official who's testified so far, and would be the most high-profile witness to testify against the president.According to Axios, Bolton was a prolific note-taker and had a habit of contemporaneously documenting everything that was said in every meeting he participated in.Visit Business Insider's homepage for more stories.Chuck Cooper, the attorney representing former national security adviser John Bolton, dropped an intriguing hint in a letter to Congress last week. read more