Alonzo Mourning, a 6-foot-10 center from Indian River High School in Chesapeake, Va., considered by many the best high school basketball player in the country, will sign a national letter of intent to attend Georgetown, his coach said last night.

"Yes, that's correct, he will be going to Georgetown," said Bill Lassiter, Indian River's boys basketball coach.

Lassiter said Mourning will hold a news conference Wednesday afternoon at Indian River and will officially commit himself to Georgetown by Wednesday's conclusion of the early signing period for college basketball recruits. Because Mourning had not done so as of last night, NCAA rules prevented any of the coaches of the schools he was still considering -- Georgetown, Maryland, Virginia, Syracuse and Georgia Tech -- from commenting.

However, Lassiter said Mourning had given word of his decision Sunday to Georgetown Coach John Thompson, Maryland's Bob Wade, Virginia's Terry Holland, Syracuse's Jim Boeheim and Georgia Tech's Bobby Cremins.

"Why Georgetown?" Lassiter said. "First of all, the coach. Also, the way he was recruited by Coach Thompson, {assistant coach} Craig Esherick and {academic adviser} Mary Fenlon. They were interested in him as a person as well as him as a basketball player. They told him the truth, that nothing was going to be given to him, he is going to have to earn it. That's something we're always trying to impress upon him."

Last season, Mourning averaged 21.8 points, 11 rebounds and 9.6 blocked shots per game for Indian River, which won the Virginia Class AAA state championship.

"He's the best big man to come out of high school I've ever seen and that says a mouthful," said Tom Young, coach of Old Dominion, one of the schools Mourning was considering earlier this year. "I've seen {Lew} Alcindor {now Kareem Abdul-Jabbar} when he was playing at {New York's} Power Memorial; I've seen Moses {Malone}; I've seen {Ralph} Sampson; I've seen J.R. {Reid}. And he's there.

"He's not going to make them forget {Patrick} Ewing," Young said, "but he's going to be right there doing everything Ewing did."

Mourning had said he liked Georgetown because of the reputation Thompson and his program enjoy, the quality of the school's academic program and the non-basketball opportunities available in Washington. Also, his girlfriend is a student at George Mason University.

"My girlfriend just told me to go somewhere where I'd be comfortable," Mourning said in an interview late last month. ". . . But I like D.C., and I've been going there a lot. It's nice up there. Plus you're right in the heart of everything. The president. The Capitol building. All the monuments. You've got the Washington Bullets. The Washington Redskins. There's always something to do in Washington, all kinds of people to meet from all over the world.

"In Washington, you've got a little bit of everything. It's like a business city, and that's what I want to major in -- business."

In September, Mourning narrowed his field of contenders to five, then invited the coaches from the finalists to his home. Cremins visited on Sept. 17, Holland on Sept 18, Wade on Sept. 21, Boeheim on Sept. 28, and finally Thompson on Oct. 5.

"It was a nice visit," Mourning said of his meeting with Thompson. "My mom liked him and everybody in the family loved him. They understood what he had to say. He stayed for a while . . . for about an hour and a half. He had a lot of things to say . . . a lot of good things to say. He really didn't sell Georgetown. He talked about the school and asked me how did I get interested in it. I told him, 'I like the school, I like the way they play. I think I can fit in there.' "

During the visit, Mourning also heard from Fenlon. "She told me the usual routine that freshmen have to go through," Mourning said. "They call her every day and tell her how their classes were. She gives them a lot of help with their work."

Mourning was determined not to make a commitment until he visited the campuses of each of the five schools. He called on Virginia, Syracuse, Maryland, Georgia Tech and Georgetown -- in that order.