Transcript for Russia investigation is closing in on the president's inner circle

investigation is closing in on the president's inner circle. A correct me if I'm wrongshal committee wanting to question a man who served at trump tower for more than a decade. He is one of his closest aides, and the date is set for president trump to meet face to face with Vladimir Putin himself. Here's ABC's senior white house correspondent, Cecilia Vega. Reporter: Tonight, ABC news has learned the house intelligence committee wants T interview a key member of the president's inner circle, his former body guard, Keith schiiler. Sources say investigators told schiiler and at least one other aide close to the president they are potential witnesses in the probe into possible ties between team trump and the Russians. Schiiler did not respond the requests for comment. A key reason investigators want to talk to him, he has known trump for years, and is just about always by the president's side. A fmer New York City police officer after the election, the president gave schiiler the sitele, director of oval office. Among his jobs, handle delivering the letter that James Comey will be fired. He was there for that visit to the Vatican, and he accompanied Jared Kushner to Iraq. Schiiler there seated at the table with top military leaders. Excuse me. Sit down. You weren't called. Sit down. Sit down. Sit down. Reporter: But it is his time on the kpran trail that garnered the most attention. Go back to your position. Reporter: After this look from his boss, it was Shiller who ushered Jorge Ramos out of that now infamous news conference. Don't touch me, sir. You cannot touch me. Reporter: It was schiiler seen outside of trump tower punching a protester in the face. And Cecilia Vega joins us from the white house. Cecilia, as the Russia investigation continues, today, the white house announced president trump will soon meet face to face with Vladimir Putin. Reporter: It will happen next week no Germany, Tom. Durm that summit. Will president trump raise the issue of Russian interference in the election? So far, we are told by the white house the agenda for that meeting has not yet been set, Tom. Cecile gentleman, thank you.

This transcript has been automatically generated and may not be 100% accurate.