State Sen. Clarence W. Mitchell III was fined $250 and placed on three months unsupervised probation yesterday for having a loaded gun in a briefcase he was carrying on board an airplane April 30.

Anne Arundel County District Court Judge Donald Lowman told Mitchell he did not believe the legislator should be stigmatized with a guilty verdict, so he gave him probation before judgment, meaning Mitchell will not have any criminal record as the result of the handgun violation.

Mitchell testified that he was just as surprised as security personnel when his Colt Cobra .38 special was found by X-ray screening equipment as he was boarding a plane for Chicago at Baltimore-Washington International Airport.

Mitchell, 43, a five-term member of the Senate, said he routinely carries the gun from his home to his Baltimore real estate office because his office has been burglarized three times. Mitchell said he had worked in his office all night and, in a rush to catch a plane, forgot to take the gun out of his briefcase.

"There will be no point . . . in considering any type of jail penalty," Lowman told Mitchell. "Frankly, I see no point in stigmatizing you with a guilty verdict. . . . It is a sad commentary on our society today when even a businessman feels compelled to carry a gun. The only thing that disturbs me with regard to your case is that the gun was loaded."

Although Mitchell had joked about the case in recent weeks, he hired three attorneys, including his younger brother Michael F. Mitchell, a Baltimore city councilman; Bruce C. Bereano, an Annapolis lobbyist; and former federal prosecutor Abbe Lowell.