After a little detective work by his staff, Sen. Roger Jepsen (R-Iowa) went to the White House last week and angrily demanded that President Reagan's top advisers discipline White House political director Edward Rollins, whom Jepsen accused of being the source of graphic, anonymous quotations months ago about how he was pressured into switching his vote on selling AWACS to Saudi Arabia.

Rollins made the remarks last October during a lecture to a Georgetown University class, Jepsen charged in a meeting with Rollins and top presidential advisers James A. Baker III and Edwin Meese. Rollins denies having uttered the words that caused the senator so much embarrassment back home.

White House chief of staff Baker, who is traveling with Reagan, promised Jepsen that he would "do something" about the matter in the next day or two, according to Jepsen press secretary James Lafferty.

The senator's aides obtained the names and phone numbers of all the students in the class. They interviewed and tape recorded the students' recollections of just what the president's aide had said in the classroom three months earlier. The class was entitled "Political Press Secretarying," and its students included a number of congressional staff members.

Among those attending the lecture was a nonstudent, John Hyde, a Washington correspondent for the Des Moines Register, who accompanied a friend who was enrolled in the class.

He later wrote an article quoting "a White House official" talking about how the White House converted Jepsen to the airborne warning and control system (AWACS) sale. Hyde now concedes that he was quoting what Rollins said in the classroom, and he says he stands by the accuracy of his quotations.

Rollins acknowledges that he lectured the class, but denies uttering any of the remarks that have caused Jepsen so much consternation. "I've made mistakes and done stupid things in the past, but on this one, I'm innocent," Rollins said.

He has outlined his denial in a four-page memo to his superiors, Baker and Meese. And his aides, in an understandable effort to buttress his denial, made available others who attended the class. They supported most, but not all of Rollins' denials--and in the one quote they felt had been uttered, they emphasized that the presidential aide was speaking in a context of the political-facts-of-life that meant Jepsen no harm or criticism.

The Register article said:

" 'We just beat his brains out,' said a White House official who was directly involved in the AWACS effort. 'That's all. We just took Jepsen and beat his brains out.' "

The instructor of the class, Chris Till, who is a longtime friend of Rollins, says the class was meeting on the eve of the Senate vote on the sales of AWACS planes to Saudi Arabia. She recalls that the presidential aide said at one point, "We beat his brains in."

Three students said it was in the context of an all-out White House effort at lobbying Jepsen and other senators.

The class instructor and several students said it was announced at the outset that Rollins' remarks were to be off the record. Reporter Hyde said he heard no ground rules given and had introduced himself by name and newspaper affiliation when all those attending introduced themselves at the start of the class.

The Register article also said:

" 'We just turned the faucet off,' said the White House official. Jepsen was told he could vote as he wished, but he could expect no further cooperation from the White House, political or otherwise. Then he was shown the door and told he was on his own.

" 'We stood him up in front of an open grave and said he could jump in if he wanted to,' said the official."

One student who was contacted independently by The Washington Post, Scott Fisher, press secretary for Rep. Larry Craig (R-Idaho), said he recalled that Rollins said something about "turning off the faucet" but thought he was speaking then of lobbying all members of Congress, not just Jepsen. Several others who attended the class did not recall Rollins saying this.

None of those contacted by The Washington Post recalled Rollins saying anything about standing Jepsen in front of an "open grave" and a spokesman for Jepsen conceded that none of the students interviewed by the senator's staff recalled Rollins making such a comment.

One student, Brad Jones, who works for a Democratic member of Congress, recalled one bit of good advice Rollins gave that night. "He talked about the importance of discretion--especially in saying things that might hit the newspapers."