A former Northern Virginia investment counselor, who authorities say allegedly absconded with more than a half-million dollars in retirement and education monies, was jailed yesterday after he peaded guilty to swindling $20,000 from a Fairfax County man.

Fairfax Circuit Court Judge Richard J. Jamborsky revoked the bond of Thomas J. Ball, 39 of Great Falls after a prosecutor said he feared Ball might flee before he is to be sentenced on June 27. Prosecutor William J. Schewe said investigators suspect that Ball has hidden some of the missing money and could use it to leave the area.

"There is a serious question about where a lot of the money is," Schewe said.

Defense lawyer Darwyn Lesh, in vigorously objecting to the action, told the judge his client has known for a year that he would be sent to prison. "If he was going to run, he would have run a long time ago," Lesh said.

The lawyer also denied that Ball has hidden money. "Not a dime has been found," Lesh said, even though Ball is the subject of 30 civil suits in Fairfax alone.

Ball pleaded guilty yesterday to a charge of obtaining money under false pretenses, as part of a plea bargain in which he agreed to accept three years in the prison and make $10,000 in restitution. Judge Jamborsky said he would accept the terms of the plea bargain, but postponed formal imposition to await the outcome of a presentencing report.

The single state charge is separate from a 21-count indictment returned against Ball by a federal grand jury in Alexandria last month. That indictment charges Ball, who operated under the name Tom Ball & Associates, with mail and securities fraud, sale of unregistered securities and perjury.

Ball and his wife, Sylvia A. Ball, 34, were charged separately with three counts of filing false joint federal income tax returns for the years 1976 through 1978.

Ball could receive up to 111 years in prison and $111,000 in fines if convicted of all the federal charges. He has pleaded not guilty, but Lesh said in court yesterday that he has discussed a plea with federal prosecutors in their case.

From 1972 until last September, Ball, according to the federal indictment, promised clients he would invest their money in securities and real estate deals, but actually used much of the money to meet his personal expenses.

In the Fairfax case, prosecutor Schewe said Ball obtained $20,000 from Leo Gulley on Aug. 31, 1977 under the guise of investing it to help Gulley raise money for his children's college education.

Instead, Schewe said, Ball used the money to pay for carpeting in his home, his Mercedes car, legal fees, and gave the rest to his wife. Ball spent the entire $20,000 in one month, Schewe said.

He later made one interest payment of $3,800 to Gulley, who lost the rest of his original investment, Schewe said.

According to the federal indictment, Ball failed to tell his customers that his business lost more that $750,000 in 1978 alone, and that he suffered involuntary bankruptcy in 1974.

A federal bankruptcy judge earlier this year again declared Ball bankrupt, after a second involuntary bankruptcy petition was filed against him by creditors. Ball has reported that his creditors claim he owes more than $2.1 million. He is disputing the amounts of many of the claims.