John Stuart Mackintosh, a Washington area football coach, was acquitted last night by a Montgomery County jury of fondling a teenage youth while he was coach of a youth league football team in 1981-82.

The Circuit Court jury deliberated almost nine hours before finding Mackintosh not guilty of child sex abuse.

Mackintosh, 51, still faces trial April 15 on a second child sex abuse charge involving the older brother of the complainant in the trial decided last night.

After the verdict was read last night, the courtroom, filled with students and friends of Mackintosh's, erupted in clapping and shouting. Afterward, Mackintosh hugged and cried with supporters.

Mackintosh, most recently the football coach at Pallotti High School in Laurel, was charged last June with fondling and touching improperly a 14-year-old youth between January 1981 and March 1982.

The alleged incidents occurred when Mackintosh was head football coach for Catholic Youth Organization teams sponsored by St. Camillus Church in Silver Spring. Mackintosh, a management analyst for the federal government, coached 24 years for the CYO, winning 14 youth football championships.

After the allegations surfaced, Mackintosh gave up his coaching post at Pallotti pending the outcome of the charges against him.

The credibility of the alleged victim, now 24, was the focal point of the six-day trial. The man testified that Mackintosh massaged and fondled him after showers at the coach's Silver Spring apartment. The man also accused Mackintosh of taking nude photographs of him and improperly touching him during weightlifting practices in the basement of St. Camillus Church and on an outing to Deep Creek Lake in Western Maryland.

Mackintosh took the witness stand to vigorously deny the allegations, saying he had never massaged the youth or touched him improperly in any way. Mackintosh described himself as a caring and affectionate coach who frequently invited players to his home and on weekend trips.

In closing arguments yesterday, Assistant State's Attorney Frank Molony described the alleged victim's testimony as courageous and convincing: "The details, the specificity, the bizarreness of it all speaks of personal, direct experience."

The complainant said he decided to tell his story publicly after receiving intensive therapy last year. He said guilt and shame prevented him from doing so earlier when "I didn't want anyone to know about it." The man, a former backup running back and defensive player on a youth team, said he had revered and trusted Mackintosh as a coach and family friend. "I thought he was the greatest man in the world."

Defense attorney William J. Rowan III attacked the man's testimony in closing statements yesterday, saying his testimony was inconsistent and conflicting and that "this evidence has not proven {Mackintosh} guilty beyond a reasonable doubt."

Rowan questioned several key parts of the prosecution case, saying that monetary gain was a possible motive because the man testified he was considering filing a civil damage suit against Mackintosh.

The abuse charge still pending against Mackintosh stems from the allegation of the man's brother, now 25, that Mackintosh fondled him during overnight stays at the coach's apartment and on beach excursions between January 1980 and December 1982.

The 25-year-old testified last week that he had seen Mackintosh fondling his younger brother at weightlifting workouts.

Rowan sought to discredit that testimony because the older brother made the allegation to authorities only at the start of the trial.