The Maryland state prosecutor's office has opened an inquiry into a 10-day trip to South Africa that Prince George's County schools chief Andre J. Hornsby accepted last year from a company that does business with the school system, Hornsby said yesterday.

Hornsby said in an interview that the prosecutor's office has asked him about the trip and whether he had disclosed it to the county school board. He declined to discuss the inquiry in detail yesterday, citing the advice of a lawyer.

"I was told specifically there's no investigation going on," he said, "but there were some questions that they wanted to ask."

As president of the National Alliance of Black School Educators, Hornsby traveled with a group of U.S. educators to South Africa in July 2003, a month after he became the Prince George's schools chief. The trip was paid for through a "scholarship" from Plato Learning, a Minnesota-based educational software company, he said.

He said he notified the school board of the trip before it hired him. Board members have confirmed that disclosure, but board Chairman Beatrice P. Tignor (Upper Marlboro) said Hornsby did not mention that the company would pay for it.

Hornsby also acknowledged yesterday that he was directly involved in the school system's purchase of nearly $1 million of software and other teaching tools from California-based LeapFrog SchoolHouse. Hornsby lives with Sienna Owens, who sells LeapFrog products to schools in Virginia. Those purchases, in June, are the subject of an investigation by the school board's ethics panel.

Hornsby said he chose LeapFrog SchoolHouse because he thought it was the only vendor that could provide the equipment needed, including laptop computer-like machines that are used to teach reading to low-income kindergarten students.

"My mother could have been working for LeapFrog," he said. "If I wanted to buy it, they're the only people that had this product. . . . It had nothing to do with anything else."

State Prosecutor Robert A. Rohrbaugh, reached Friday, declined to say whether his office was looking into Hornsby. Rohrbaugh did not return a phone call yesterday. His office was created in 1976 to investigate allegations of misconduct by public officials, including ethics violations.

Hornsby called the prosecutor's inquiry a "nonissue." He said that it began several weeks ago, after the Baltimore Sun disclosed details of the South Africa trip, but that he has not met with a representative of the prosecutor's office.

Prince George's schools were buying products from Plato before Hornsby arrived from New York. Since he became the county schools chief, he said, the system has bought $36,000 worth of products from the company. Hornsby said that members of his staff have been considering other purchases but that he has not been directly involved in those discussions.

"I have not had a conversation with Plato about doing more business," he said.

In the interview yesterday, Hornsby, 51, offered a spirited defense of the South Africa trip, the LeapFrog SchoolHouse purchases and his conduct in an ethics controversy during his tenure as superintendent in Yonkers, N.Y. The outspoken administrator, who has clashed with politicians and teachers union leaders in Yonkers and Prince George's, called himself the victim of "character assassination" by a "cast of characters" that he would not name.

"You think I haven't pushed people's buttons since I got here?" he asked. "You think there's a lovefest going on?"

The school system has been doing business with LeapFrog since 2002, but spending on LeapFrog software has increased substantially from the roughly $500,000 that Hornsby said was paid to the company before he arrived in 2003.

At the time of the June purchases, Hornsby said, the system had federal Title I grant money that had to be spent quickly or returned. Hornsby said he directed his staff to "engage in a conversation and start negotiating terms" with LeapFrog. Yesterday, he called it "an excellent use of money."

He declined to discuss his relationship with Owens but did say she was not involved in his decision to buy the products. "Nobody can influence me. I'm not influenceable," he said. "If I decide to do something, it is the best decision for the children in this county."

Asked whether Owens profited from the business deal, he said, "I have no knowledge of her profiting from the purchase."

Officials at LeapFrog said Owens, 26, handles sales only in Virginia and was not involved in the Prince George's transaction, which was handled by Maryland sales representative Debora Adam. Attempts to contact Owens last night were unsuccessful.

During a more than two-hour interview yesterday, Hornsby offered no apologies or regrets. "I know how to do my job, and I know how to separate personal from business," he said.

He said the criticism in Prince George's is reminiscent of a controversy in Yonkers over a contract the school system there awarded to Xerox Corp., despite a lower bid from Minolta.

Months after he was fired in June 2000, following clashes with the mayor of Yonkers and labor unions, the city's inspector general noted in a report that Hornsby had accepted from Xerox Corp. an expenses-paid trip to the Ryder Cup golf competition in Boston. The trip came after the school system entered into a copier contract with the company, according to the report. The inspector general in Yonkers also criticized his acceptance of a hand-held computer from Xerox, before a contract was signed.

Yesterday, Hornsby said the lower bidder's proposal did not meet the school system's specifications, which is why Xerox got the contract.

Hornsby said he had permission from the Yonkers school board to take the trip to the Ryder Cup. As for the hand-held computer, he said he won it at a raffle at a conference and gave it to his secretary.

The 2003 South Africa trip was organized by the National Alliance of Black School Educators and sponsored by Plato and Gateway, another educational software company. Hornsby said Plato paid for him because he was then the president of the alliance.

Though his tenure as president ended last November, he has remained active with the group and went to South Africa a second time this summer. That time, he said, he paid the $2,500 fee, which included airfare, hotel and food.

On his annual ethics form, filed Jan. 31, Hornsby was asked whether he had received gifts worth $25 or more from anyone who had a contract with the school system. He answered no but said he had professional relationships with many companies doing business with the school system.

Last week, in response to the LeapFrog purchases, two Maryland legislators said they plan to propose a bill to strengthen ethics laws for school officials across the state who have purchasing power.

"What Dr. Hornsby has done -- right, wrong or indifferent -- is to put the [Prince George's school board] in a very tenuous position," said Del. James W. Hubbard (D-Prince George's), one of the two legislators.

Ronald W. Rebore, a professor of educational leadership at Saint Louis University in Missouri, said he has recommended that all school districts have internal auditing departments to look for conflicts of interest and misspent funds. At the moment, he said, "very few have them."

Staff writer Jay Mathews contributed to this report.

Hornsby said officials had questions "they wanted to ask."