The Army two years ago had enough evidence of sexual misconduct to court-martial a former chief of pediatrics at Fort Belvoir, who was charged this week with the forcible sodomy of a minor, but let him resign, according to a Defense Department investigation.

Civilian medical boards were never notified of the allegations and Dr. Arthur C. Andreasen began private practice at the Kaiser Permanente health organization soon after he left the Army in March 1983.

Joseph Sherick, inspector general of the Defense Department, wrote on Dec. 28, 1984, to William Mayer, assistant secretary of Defense for health affairs, that he was greatly concerned that the Andreasen case would condone "the release of highly questionable physicians into an unsuspecting civilian medical community where further acts of medical misconduct may be committed."

The inspector general had studied the case of Andreasen, who was a lieutenant colonel, as part of an attempt to initiate mandatory procedures for reporting allegations of medical misconduct of military doctors to civilian licensing boards.

Sherick asked that the Army review its decision to allow Andreasen to resign without reporting allegations of sexual misconduct to any outside medical board. However, according to an official involved in the investigation, the Army decided that proper procedures were followed and nobody was notified of the allegations of sodomy against Andreasen.

"Despite evidence that included a sworn detailed statement by the alleged victim, a qualified admission by Lt. Col. Andreasen and the opinion of the staff judge advocate that there was enough evidence for a court-martial, the medical command elected to issue an administrative letter of reprimand and accepted Andreasen's resignation," Sherick's letter stated.

"The thing that is so sickening about this whole mess is that the Army just cut him loose," said one person familiar with the military investigation. "They sent glowing, wonderful recommendations on his behalf."

Andreasen's letter of reprimand, which was not released to civilian medical authorities, states that "he did not properly counsel a patient who became excited during a genital examination."

A March 8, 1983, letter from the chief of professional services at Fort Belvoir's Dewitt Hospital to Arlington Hospital describes Andreasen as an outstanding doctor but says that in one instance he "misunderstood the conduct of a genital exam."

Andreasen is registered as a pediatrician on the staff of Arlington Hospital, and officials there said they could not comment on his personnel record because it is private.

"I wish I could say something to erase this and make it right," said Tansill Johnson, public affairs officer for the Army surgeon general's office, which corresponded with Fort Belvoir officials about what action to take in the case. "What happened wasn't right. It would never be right."

Repeated attempts to reach Andreasen and his attorney for comment were unsuccessful.

This week, Andreasen was charged by Alexandria police with forcing a boy to commit sodomy more than 10 times during a two-year period. Police said the youth was a military dependent, and that the incidents began at Fort Belvoir and continued at an unlicensed clinic, the Adolescent Counseling Service at 217 S. Payne St. in Alexandria, after Andreasen left the Army. Andreasen apparently was working there after he joined the staff of Kaiser Permanente, one of the nation's largest health care organizations.

"The kid was desperate, he wrote several suicide notes," said Alexandria police investigator Larry Agne. "Like a lot of people in this position he was too frightened and humiliated to do anything for a long time."

Police said Andreasen called the boy's mother two months after leaving the military and asked how he was. When she told him her son was suicidal he volunteered to see the boy immediately, although he had no psychiatric training, according to Kaiser Permanente's records.

Andreasen resigned his job at Kaiser Permanente on Nov. 26, 11 days after the alleged victim reported him to the police.

"The Army often lets their guys just cop out," said Bryant Galusha, executive vice president of National Federation of State Medical Boards. "They say you get the hell out of here and we won't do anything."

According to Defense Department officials, the 14-year-old boy promptly reported the alleged incident of sodomy at Fort Belvoir. A criminal investigation was conducted, and Andreasen admitted that his mouth touched the boy's penis, according to the officials. Within a week, however, Andreasen submitted a written statement denying everything he had told the initial investigators.

Galusha and several military officials said that today it would have been much more difficult for Andreasen to resign without disciplinary action.

"That which the Army did was correct by their regulations at the time it occurred," said Dr. Jarrett Clinton, deputy assistant secretary of defense in charge of quality assurance. He said the armed services today would prevent a doctor in a similar situation from practicing while allegations were investigated, and that they are much more vigorous in prosecuting medical officers. In 1984, the rules were changed to require the armed forces to report any formal disciplinary action to the National Federation of State Medical Boards.

Andreasen graduated from Vanderbilt Medical School in 1971, according to Kaiser Permanente records. He worked as an intern at Vanderbilt and a resident at the University of Kentucky Medical Center. He spent a year on a fellowship in adolescent medicine at Walter Reed Medical Center and served at Fort Knox from 1976 to 1980, when he went to Fort Belvoir.