James Capitanio, 64, who was federal Judge John J. Sirica's courtroom clerk during the Watergate trials, died at his home in Washington Monday after an apparent heart attack.

As Sirica's clerk, Mr. Capitanio - or "Cappy," as he was known to courthouse acquaintances - was the person who read aloud the jury verdict that convicted former top Nixon aides John N. Mitchell, H.R. (Bob) Haldeman and John D. Ehrlichman, at the end of the Watergate cover-up trial.

Mr. Capitanio, who lived at the U.S. Soldiers and Airmen's home, also had the duty of keeping the mass of White House tapes and documents secure and in order during the trial. He received praise from attorneys, coworkers and reporters for his assitance during his service with Sirica.

In a letter at the close of the trial in January 1975, Sirica praised Mr. Capitanio by saying: "Your efficiency, dedication and know-how made an all but unmanageable proceeding seem to flow with ease."

Mr. Capitanio served for more than 20 years in the U.S. Army, retiring as a master sergeant in 1963 after being the chief legal clerk in the office of the staff judge advocate. He worked briefly with the Department of the Interior and the D.C. Register of Wills before coming to the U.S. District Court as a deputy clerk in the November 1963.

Survivors include a sister, Melina Capitanio, of Mahanoy City.