Transcript for The country reacts in shock to Nixon's Saturday Night Massacre: Part 8

president that there was a cancer growing on the presidency. What did the president know and when did he know it? At that point in June of 1973 it was John W. Dean, a little known former counsel to the president, versus Richard Nixon-- a man the country had known for 30 years, and now president of the United States. Whom was the country going to believe: Dean or Nixon? The key witness in the minds of the people who were there and later on was Alexander Butterfield. The subcommittee will come to order. Alexander Butterfield was sort of the president's personal assistant who would keep the trains running on time, keep the flow of people and paper, in and out of the oval office. He saw everything. Butterfield was called just to see if he had anything to say that was worthwhile. And he did. I was told "The president wants you to get a taping system." But the idea was it's not just gonna be a little thing in a desk draw. And he wants it on all the telephones -- office phones and in the oval office. When I briefed the president, it was just the president and I. How does that work, Alex? Does it work with you here? Uh, no. I'm going to monitor this . I don't want it monitored you see, what happens when a record is made, a tape? A tape is made. Yes, sir. I took him through it. He was embarrassed the whole time. He didn't like me tellin' him about this stuff that he'd had put in. And I do believe he needed to know where the microphones were. And they were on the base of the lamps over the mantelpiece. And then I hated to tell him that they'd drilled these holes in his desk. He was embarrassed that I was telling him about this thing that he had asked -- that it be installed. He would like to have asked that unbeknownst to anyone. Listen, this wasn't a happy day for me. I knew there was skullduggery going on in the white house. Mr. Butterfield will you stand and raise your right hand? My name is Alexander porter Butterfield. Fred Thompson who was the counsel for the Republicans. Mr Butterfield I understand you previously were employed by the Whitehouse. Asked the question. Mr. Butterfield, are you aware of the installation of any listening devices in the oval office of the president? I was aware of listening devices. Yes sir. And at that point, like all I knew how huge that was. And at that point, like all the other reporters in the room, I said to myself, "The jig is up." If those tapes prove that Richard Nixon orchestrated a cover-up let alone whether they proved that he had ordered the break-in of the watergate, he's cooked. To all of the people I knew and my friends they were probably saying that son of a He's hurting our man. I understood Nixon. I-- I-- I honestly understood it all very well. I knew Nixon so damn well. So I hated to be the guy. Do you ever hear any of these tapes being played? Yes, sir. I did. Once Alexander Butterfield disclosed the existence of the taping system, the real challenge then, for the Ervin committee, was finding a path to subpeona those tapes. The senate recognized it had the power to ensure that there would be a full and complete investigation. And they exercised that power. Richardson, appointed Archibald cox, a Harvard professor to be the special prosecutor. The guidelines or charter for the special prosecutor state that he will have full authority. The special prosecutor was given a mandate of Independence to investigate watergate no matter where it went. When the tapes were revealed. The pressure is on the president to produce those tapes. Or run the grave risk that public opinion will decide he can't because of what is on them. Cox asked the white house to give him the tapes. And Nixon refused. Nixon was raging, okay, in the summer of 1973. He's so angry. He's angry because Archibald cox is putting pressure, he wants the tapes. Whether we get them now is an issue for the courts. I think the powers of the presidency had never been challenged before, the way they were when the special prosecutor subpoenaed Nixon's white house tapes. And he just can't stand what's going on, and he wants to -- he wants to get rid of Archibald cox-- I mean, to fire him. And his people say, "No, Mr. President. Don't do that; that's gonna cause more trouble. Worst thing you can do is to fire the head of an investigation; it makes you look guilty. Ultimately the court of appeals ruled that the tapes had to be turned over. The president had lost any patience. He said, "Get rid of cox." My Richardson I can't fire cox. Mr Richardson, can we see you for a bit? Richardson said, "I can't fire cox. I mean, can't possibly fire him. I'm gonna resign first." So he resigns. There will be an announcement out of the white house. Then the order was given to the deputy attorney general William ruckelshaus to fire cox, the special prosecutor. And ruckelshaus refused. Raise your right hand. I was attorney general about twenty minutes. I found out that twenty minutes is not long enough to get your picture on the wall. I really had no recourse but to refuse to carry out the directive and to resign. To this day ruckelshaus doesn't know if he was fired first or resigned first. But in any case, he leaves the scene. The third person-- in the list of succession is the solicitor general, Robert bork. It's bork who finally does the deed and fires cox. Well, by this time, the nation was up in arms. This was called "The Saturday night massacre." We were horrified, this was not what we considered to be the role of the president or how democracy functions. So it looked like not only was cox gone, but the investigation was over. So many Americans thought, "Oh my god, this is a coup d'etat. Basically, the president has seized full control of the special prosecutor's office. They are impeding our operations right now. The white house the executive branch acted as if it was actually going to crush the entire investigation. Our office had been seized and to us it was a clear attempt to obstruct the investigation, to interfere. Impeach Nixon now! Impeach Nixon now! And the American people were outraged. They said basically, "You know, we're not a banana republic. We have a system of laws here even if it's the president of the United States, no one is above the law." And now, the public opinion tide swung very strongly against Richard Nixon because that Saturday known as the Saturday night massacre did it. And who did it? Richard Nixon did it to himself. Impeach Nixon now! Impeach Nixon now! I have no intention whatever of walking from the job I was elected to do.

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