A Nevada man who is wanted on fugitive charges in that state and who had allegedly hand-delivered a written plea for help to the office of Sen. Chic Hecht (R-Nev.) earlier this week, was arrested entering a Senate office building after authorities were warned he might be dangerous.

James D. Johnson, 43, of Las Vegas, was charged Tuesday with carrying a gun on Capitol grounds, a federal offense, after Capitol Police found a loaded .38 caliber revolver in his car, which was parked near the 100 block of C Street NE, near the visitors entrance to the Dirksen building, police said yesterday.

Johnson delivered a typewritten letter to Hecht's receptionist in the Hart Senate Office Building Monday, and left without signing the register or giving his name, Senate sources said.

The letter, with no signature, but with the name "James D. Johnson" typed at the bottom, said, "I am writing to you out of total desperation as a last resort . . . . "

It explained some of Johnson's plight, and concluded, "I hope there is something you can do for me. You must believe me when I say that I will never go back to Elko County in Nevada alive." A copy of the letter was obtained by authorities.

Hecht said yesterday, "Because he Johnson is being held in jail, because of the case, I do not want to comment on anything." Johnson is being held without bond and is scheduled to appear in D.C. Superior Court Monday, according to prosecutors.

Capitol Police Capt. Robert Howe said that there had been "no specific threats against the senator," but that Las Vegas authorities contacted Capitol Police early Tuesday. They reported that Johnson, who had been charged with violating Nevada gaming laws and with failure to appear at a court hearing, was headed for Washington to see Hecht and might be dangerous, according to Howe.

On Tuesday, plainclothes officers were stationed at entrances to the Hart building and to Hecht's office, Howe said, and a description of Johnson was circulated to police officers, who normally guard all entrances to House and Senate buildings.

Howe said Johnson was arrested at 6:25 p.m. Tuesday as he came through the visitors' entrance to the Dirksen building. That entrance also provides access to the Hart building.

The letter to Hecht said, "I have been a victim of what is known as 'frontier justice' or rather injustice." It said that Johnson was a Boy Scout and Cub Scout counselor and an usher at his church. His problems with the law, it asserted, stemmed from a misunderstanding with Nevada authorities.