ANDRE J. HORNSBY, who took command of Prince George's County's battle-scarred public school system a little over 15 months ago, has stepped on more than a few establishment toes in his full-court press to turn things around. Modesty is not his strong suit, and he is quick to brush aside criticisms of his decisions. Several of those decisions -- made before and after the county Board of Education hired him -- are now prompting inquiries by the Maryland state prosecutor's office, state legislators and some members of the board. The actions involve questions of ethics, and they merit thorough examination.

Officials are looking into Mr. Hornsby's dealings with vendors, following a recent Baltimore Sun report that he had traveled to South Africa in July 2003 on a trip organized by the National Alliance of Black School Educators. The report said his expenses were paid for by Plato Learning, a company that the school system has done business with and is considering giving another contract to. Mr. Hornsby said Plato paid because he was then president of the alliance. This may be customary practice, but any school officials dealing with vendors ought to steer clear of gifts from them.

Months after Mr. Hornsby was fired in 2000 as superintendent of the Yonkers, N.Y., school system after a run-in with the mayor and labor unions, the city's inspector general reported that Mr. Hornsby had taken a trip to the Ryder Cup golf competition in Boston, with all expenses paid by Xerox Corp. The report noted that this came after that school system had entered into a contract with Xerox; it also noted that Mr. Hornsby had accepted a handheld computer from Xerox before a contract was signed. Xerox was not the lowest bidder, but Mr. Hornsby says the competing proposal did not meet the school system's specifications. He said he had permission from the Yonkers school board to take the trip; he said he won the computer at a raffle at a conference and gave it to his secretary.

The Sun also has reported that Mr. Hornsby did not disclose that he lives with a saleswoman for LeapFrog, a company that sold about $1 million in software and teaching tools to the county system in June. A spokeswoman for Mr. Hornsby said he did not have to disclose that relationship on his annual ethics form, filed in January, because the woman was not a LeapFrog employee at that time. Besides, Mr. Hornsby said, the woman sells products in Virginia and was not involved in the Prince George's deal.

Mr. Hornsby may have played by the rules in every instance, but those rules ought to be tightened. He says flatly that "nobody can influence me." In an interview reported Tuesday by The Post's Nancy Trejos and Eric Rich, the schools chief said he is the victim of "character assassination" by a "cast of characters" that he would not name. "If I decide to do something," he said, "it is the best decision for the children in this county." That remains to be seen. True, in a relatively short time in Prince George's Mr. Hornsby has made some dramatic changes affecting every classroom in the rapidly expanding system, and many hold promise. We will examine them at a later date, but the immediate focus should be on the ethics questions that beg for more than Mr. Hornsby's cavalier dismissal. At the very least, he has exercised bad judgment.