After crashing an armored vehicle through a picture window to get a better look inside the house where George Henry Butler was holed up with a gun, a Prince George's County SWAT team observed the 91-year-old man sweeping up the debris with a broom and dustpan and then making a sandwich, as if oblivious to the siege around him.

Police said Butler--a wisp of a man known around the eastern county's farming area as a gentleman since the days when he was raising cattle--also paid no mind to the body of James Thomas Newman, 59, a beloved nephew killed when Butler apparently failed to recognize him. When ambulance workers pulled up at Butler's Leeland Road home, they found him mowing the grass a few feet away from Newman's body.

Less than two weeks earlier, Robert Davis Jr., a 74-year-old retired postal worker, slipped behind the wheel of his 1998 gray Cadillac, drove to his sister's D.C. apartment and allegedly shot her to death with a .38-caliber handgun when she returned from the grocery store. D.C. police say Davis killed his 69-year-old sister, Lucille Shropshire, because he believed she had cast a deadly voodoo spell on him.

Two area elderly men, each apparently gripped by powerful delusions, allegedly exploded in violence in the last two weeks, lashing out at loved ones in a fury that seemed to defy reason. But to people whose family members suffer from Alzheimer's disease or other age-related brain disorders, the bizarre flashes of unpredictable behavior are all too familiar.

"Day in day out, there are Alzheimer's patients who get combative," said William E. Reichman, president of the American Association for Geriatric Psychiatry. "They get aggressive. But very often this doesn't come to the police's attention in dramatic fashion."

As the illness takes its course, some patients become combative. They may scream or spit at family members and caretakers or fly into a fit of unprovoked scratching, biting or kicking, according to experts in the disease. But only in extraordinary cases does it reach a sustained level of extreme violence.

"It's extremely rare that there would be . . . [an] outburst of violence by an Alzheimer's patient, because the cognitive abilities necessary to plan and carry out such an attack are usually impaired," said Steven Ferris, executive director of the Silberstein Aging and Dementia Research Center at the New York University School of Medicine.

When police are called to intervene, Reichman said, it is usually because of a less violent confrontation.

"Very commonly, a patient will turn to a spouse of 40 years and say, 'Who are you? What are you doing here? Get out of my house,' " Reichman said. "The patient may get physically aggressive and push the spouse out of the house. Or the patient may try to flee."

It's a situation that's becoming more common. As the population ages, more and more people become susceptible to age-related dementias that befuddle and disturb a person's thinking.

Alzheimer's, far and away the major cause of dementia, affects about 3 million to 4 million people. The disease strikes about one in 10 people older than 65 and nearly half of those older than 85. As baby boomers gray, the number of sufferers is expected to grow. The Chicago-based Alzheimer's Association told Congress that the number of Americans suffering from Alzheimer's will double by 2030.

"These are problems that as a society we increasingly are going to have to confront," Reichman said. "There is an epidemic of Alzheimer's disease."

Dementia describes the progressive breakdown of intellectual capabilities, often marked by confusion, chronic memory loss and personality disturbances that accompany pathological changes in the brain.

Circulatory disorders that trigger mini-strokes deep inside the brain contribute to at least 15 percent of all dementia among the elderly. Another degenerative brain disorder--known as dementia with Lewy bodies--combines symptoms of Parkinson's disease and Alzheimer's but also includes hallucinations and accounts for 15 to 20 percent of the dementia cases.

Alois Alzheimer, the doctor who identified the disease that bears his name in 1906, observed signs of paranoia and aggressive behavior in some of his patients. But experts say much of the medical literature has focused on the cognitive effects of the disease.

"I think the common lore is that Alzheimer's disease is a severe form of forgetfulness," Reichman said. But studies, cited by the University of Rochester's Medical Center in a publication called "Aggression in Patients With Dementia," suggest that up to 70 percent of people diagnosed with dementia develop significant behavioral problems in the first six or seven years of illness. The report included an analysis of 222 geriatric admissions to state hospitals and found that 63 percent were violent and 8 percent used guns.

Even seemingly minor episodes of violence can have deadly results. In October, an 83-year-old Illinois woman died from injuries she sustained in a nursing home when a 66-year-old dementia patient started screaming, grabbed her and shoved her into a wall. A year before that, a violent fight between two Alzheimer's patients at a Louisiana nursing home led to the death of a 79-year-old patient.

Deirdre M. Johnston, director of forensic psychiatry at the Department of Psychiatry and Behavioral Medicine at Wake Forest University School of Medicine, has suggested that dementia could trigger violent episodes among World War II and Korean War veterans who suffered from post-traumatic stress disorder.

Writing in the January issue of Journal of the American Geriatrics Society, Johnston reviewed the case of a 77-year-old World War II combat veteran who constructed a fort out of living room furniture and ambushed his wife with a .22-caliber rifle when she returned from the grocery store. The 60-year-old woman, who survived the attack, reported that her husband had suffered from nightmares and episodes of confusion leading up to the attack.

Johnston said more research is needed to identify possible risk factors that may cause a person with dementia to undergo profound, potentially violent changes in behavior.

"It is known that people with dementia can develop paranoid symptoms--but not everybody develops paranoid symptoms," Johnston said. "We don't know why some people with dementia become aggressive, and some people don't."

As SWAT teams took up posts around Butler's home Friday, family members told police that he was hard of hearing and suffering from Alzheimer's, said Maj. William Richards, a member of the Prince George's County Special Operations Division.

Family members also told police that Butler displayed symptoms of paranoia. He fretted about burglars and trespassers, having booby-trapped windows and doors with string to detect intruders. A few weeks earlier, family members told police, Butler fired a weapon at someone who entered his property--a report police have not been able to verify.

Prince George's Police Chief John S. Farrell said Butler's age and mental state made the episode much more sensitive, likening the incident to a full-blown hostage situation or one involving children. SWAT team members worried that conventional, non-lethal tactics to subdue a gunman--such as a gun that fires rubber batons, or even police dogs--might kill Butler, just 5-feet-2 and 120 pounds.

"There was a lot of restraint on the part of our officers, and there was also a lot of empathy," he said. "It was a very sad situation. He could be anyone's grandfather or father, and everyone can relate to that."

Armed with a .22-caliber rifle and a double-barrel shotgun, Butler shot at police officers at least four times. Having ripped the telephone out of the wall, Butler also refused to make contact with police officers. "Come on in and get me!" Butler yelled, according to police.

After first checking with the family to make sure that Butler had no respiratory problems, police fired teargas around 2:10 a.m. Saturday. Eighteen minutes later, however, Butler was seen opening the refrigerator.

"The first hope was that this man would fall asleep and that we could all go home," said Deborah Rachlin, a psychologist who advised the police during the showdown.

But Butler remained awake through the nearly 32-hour siege, and police officers marveled at his stamina. By 6:18 a.m. Saturday, police had fired 37 cartridges of teargas and pepper spray into the house--so much that when police finally entered the house, the gas still was overpowering.

Finally, around midnight Saturday, Capt. Steven L. Long gave the go-ahead to disable Butler with a robotic water cannon used by the county's fire department to disarm suspected bombs. Viewing the robot's progress through a color video screen, Long saw Butler peek around a corner, wave at the robot and say something.

"He looked like a tired, 91-year-old man," Long said. Reluctantly, Long said, he pressed the button that fired a jet of water to disable Butler. Butler was knocked to the ground and fractured a leg.

Butler shed no light on his actions afterward. When police reached him around 2 a.m. and took him into custody, he told them: "I had to do it."

Staff writers Tracey A. Reeves and Jamie Stockwell and staff researcher Bobbye Pratt contributed to this report.

Effects of Mental Illness

One study of Alzheimer's disease found a high percentage of patients who experience delusions, hallucinations or misidentifications that can cause a patient to become frightened and, in some cases, violent.

Prevalence and type of psychotic symptoms in 170 probable Alzheimer's disease patients:

Symptom Percentage

Delusions 43.5%

Persecutory 73.0

Reference 14.9

Jealousy 9.5

Grandiose 1.4

Somatic 1.4

Other 28.4

Misidentifications 30.0%

House is not patient's home 51.0

Strangers are living in the house 29.4

Own reflection is someone else 21.6

Illusion 7.8

Caregiver is an imposter 2.0

Hallucinations 23.5%

Visual 85.0

Auditory 45.0

Tactile 2.5

SOURCES: "Psychosis and Physical Aggression in Probable Alzheimer's Disease," by Lynn H. Deutsch, Frederick W. Bylsma, Barry W. Rovner, Cynthia Steele and Marshal F. Folstein, American Journal of Psychiatry, September 1991