A 27-year-old man under treatment for burns suffered in a suicide attempt was shot in the head and fatally wounded at Walter Reed Army Medical Center yesterday. His father, a retired Army lieutenant colonel, was arrested and charged in the shooting.

Authorities said Martin Stephenson, the patient, was apparently in his room in a building of the hospital that is near Georgia Avenue NW, when he was shot in the head about 9 a.m. with a 9 mm pistol. He died at the hospital at 6:15 p.m. yesterday.

The father, Stanley Stephenson of 4901 Taney Ave., in the Seminary Valley section of Alexandria, was arrested at the hospital before his son died, and was charged at first with assault with intent to kill. The charge was later changed to homicide, D.C. police reported.

According to one report, the father, an engineer who worked as a civilian at Fort Belvoir after leaving the Army, was taken into custody at the hospital about 11 a.m. after he met with a chaplain there.

One of Stephenson's neighbors, who had worked with him in the local civic association, said the retired Army officer was a "very pleasant man" who had been "under a great deal of strain" since his son's suicide attempt about 2 1/2 years ago.

D.C. police homicide detectives declined last night to discuss a possible motive in the shooting.

Since the suicide attempt the son, who had a history of psychiatric disorders, had received almost constant medical care, and had undergone protracted periods of hospitalization, according to sources familiar with the case. They said the son had entered Walter Reed again on Thursday for treatment connected with burns suffered in the suicide attempt.

In that incident, which reportedly occurred in the family back yard, the son doused himself with gasoline and set himself on fire, according to the sources. They said he lost one or more fingers and suffered burns over about 60 percent of his body.

Surgery had been scheduled for yesterday to correct problems connected with scars left by the burns, the sources said. However, the surgery was canceled when the son reportedly declined to cooperate in the planned treatment.

According to sources, the father went to the hospital yesterday morning to pick up the son, who reportedly was cared for at home by the father much of the time between periods of hospital treatment.

The son was in a room on Ward 66, which accommodates ear, nose and throat and plastic surgery patients. There was a report of an argument in the room around 9 a.m., according to one source.

Shortly afterward, according to a Walter Reed spokesman, a doctor found the younger Stephenson shot in the head and critically wounded.

D.C. police said the wound was inflicted by a 9 mm Luger pistol. While the doctor began emergency medical treatment, authorities were summoned. They included the military police, the Army's Criminal Investigation Division, the FBI and police from the city's 4th District.

About two hours after the shooting, the father was taken into custody in the hospital building, according to the Walter Reed spokesman.

D.C. police homicide detectives said Stanley Stephenson was being held last night in the central cell block at police headquarters and would be arraigned this morning.

An attempt to reach the victim's mother was unsuccessful. A woman who answered the telephone at the Stephenson home in Alexandria declined to speak with a reporter.

One of Col. Stephenson's neighbors described him last night as appearing nervous and edgy since his son's suicide attempt, and as seeming to be under a good deal of pressure.

"There was considerable stress that man had been under for . . . at least 2 1/2 years," said the neighbor, who declined to be quoted by name.

Col. Stephenson was "awful quick moving, awful jumpy, awful nervous," the neighbor said. "He was under a great deal of strain. You could tell that by the way he acted."

The neighbor said that he understood that the son's treatment had also imposed a severe financial burden on the Stephenson family, although a Walter Reed spokesman said it appeared that the son, despite his age, qualified for treatment there as a dependent of a military family.

Residents of the Stephensons' neighborhood of single-family homes about one mile east of Rte. I-95, described the retired officer as a good neighbor, who was quiet and hard-working, and a former Boy Scout leader who was active in community affairs.

One of them said that the father had been burned on the arms when he went to the aid of his son in the incident in the back yard.

Those interviewed last night indicated that the father had said little since about the incident.

"He never said word one about it," said one man who lived nearby, and "I felt it was none of my business to inquire." The incident "just wasn't discussed," another neighbor said. A third said he once asked the father whether he knew the reason for his son's action. "He said, 'no,' " the neighbor said.

Several neighbors said they knew little about the incident and never understood it to be a suicide attempt.

Although one neighbor who had known Col. Stephenson for years said he seemed to have grown more nervous since the son's suicide attempt, another said he had discerned little change.

This neighbor characterized Stephenson as being for many years a man who "gets jumpy in his speech" and is "somewhat hyper . . . but not excitably so."

After retiring from the Army, neighbors said, Stephenson retired a second time, from his civilian job at Fort Belvoir, about three years ago.

They said his wife, Marilyn, works as a federal government nutritionist, and that an older son with children of his own lives in New York.

One neighbor said that Col. Stephenson flew the American flag daily from a pole that projected from the porch of his house. But, the neighbor said, the flag was not flying yesterday.