For almost four years, John Thompson, Georgetown University basketball coach, hid the fact that Derrick Jackson, now the Hoyas' all-time leading scorer, is the first cousin of the late George Jackson, one of the so-called Soledad Brothers.

"I wanted Derrick to be known for what he has done," Thompson said recently, "not because he was George Jackson's cousin."

Today, there is no doubt that Derrick Jackson has established his own identity. He is the first player Thompson ever featured on the cover of the team brochure. He is a team captain whose role Thompson has expanded beyond the ceremonial.

He was, in Thompson's words, "my mortgage" for the early success in the surge of Georgetown basketball to national prominence. When Thompson recruited the 6-foot-1 guard, he walked into his Wheaton, Ill., home and bluntly told him, "We don't want you to come to Georgetown. We need you to come."

At the time Jackson was considered a far better baseball than basketball prospect. He turned down an offer by the Texas Rangers because he wanted an education. So it came down to deciding between his only two major offers, from Georgetown and Boston College.

Jackson is deeply religious, a leader in the Fellowship of Christian Athletes. He said he prayed and, "The Lord told me to go to Georgetown."

It is advice that Jackson has not regretted. He is nearing a degree in public administration - he said he would like to restore some honesty to government - and the Hoyas are on the verge of their third NCAA appearance in his four years.

They will begin play in the ECAC playoffs tomorrow night against Virginia Commonwealth at George Washington's Smith Center and need two victories to make the NCAA playoffs for sure.With a 21-5 record, they still have an outside shot at an at-large bid should they lose in ECAC play.

All basketball players dream of national championships, and Jackson is no exception. The nocturnal dreams have increased in frequency this season. But, unlike those of most players, Jackson's dream does not end with him sinking the final shot for victory.

"What I picture is that we're three points up with five seconds to play and we've got the game clinched," he said. "When the game ends, everybody's all over the floor. Everybody on the team said they would cry if they won the national championship, and I'd be crying right along there with them."

Such a scenario may seem to indicate a certain amount of humility. Yet, in his way, without being arrogant about it, Jackson exudes his confidence, as befits a man who likely will get some mention when the wire-service All-America teams are issued soon.

He got that feeling shortly after arriving at Georgetown. Although Wheaton is a Chicago suburb, Jackson was a deprived youth when it came to playground basketball competition. He also had read about those hotshots at Maryland - John Lucas, Brad Davis and Mo Howard.

"When I got to Georgetown, there were a lot of players and guys who told me how they had done versus this pro here and that pro there," Jackson recalled. "I had never really gotten to play against anybody that caliber.

"But I was holding my own against these guys. So I told myself I must be able to play."

He said that he had read so much about those Maryland players that he was in awe of them the first time he played them.

"They were good, but they weren't like I pictured them to be - like gods," Jackson said. "I was saying, 'I can't handle them.' Mr. Thompson told me I shouldn't be saying that. You should say, 'I can handle them.'

"Just because a player's name is in the paper all the time doesn't mean he's on a pedestal. I began to realize that was true, and that I could play with anyone in the country."

In fact, Jackson has discarded his high-school idols, David Thompson and Walt Frazier.

"Now I don't have any idols," he said. "I just want to be me myself now. Next year I might be playing against them and you can't play against your idol. You give them too much respect."

Jackson never met his well known cousin George, who was slain in an alleged prison escape in 1971 and became a martyr for black activists. It was while George Jackson was at Soledad that he wrote a series of letters that were later published and replaced Eldridge Cleaver's "Soul on Ice" as the activists' leading commentary on the role of the Ibakc man in America.

"It has made me more conscious and aware of the situation in the United States," Jackson said. "I'd like to straighten some of that stuff out."

Yet, Jackson said he finds that nearly impossible. "Dealing with discrimation and prejudice come from within a person. It has to go away with time."

So, Jackson spends his time thinking how he can help improve government and he concludes, "by bringing a little honesty into it."

"I did a paper on the CIA and found one of their low characteristics was honesty, it seems."

But, for now, Jackson will be concentrating on advanced hoops the next few weeks.

Jackson believes the Hoyas can reach the NCAA final four. Not many people agree with him now. But, then, he said, not many people thought he would be this good a player either.

"When people say I can't do something," Jackson said, "that gives me the incentive to try harder. I'm going to give it 200 per cent and try to accomplish it. The people could be right, but I'm still going to try."