Ruth Allen disagreed with her brother’s opinions regarding care for a third sibling who had suffered a stroke, her husband said, and sparks flew when the pair met for breakfast at their mother’s Reston home Tuesday.

After the conversation grew heated, George Allen said, George Hamilton got a gun and shot his sister in front of their mother, 91-year-old Marion Hamilton. Fairfax County police took Hamilton, 59, into custody Tuesday, charging him with the slaying of Ruth Allen, 68.

Police declined to comment on a motive for the shooting or to confirm George Allen’s account — which he attributed to conversations with his mother and police — but did confirm that a third family member was home at the time of the incident.

“I keep telling people this is what happened,” George Allen said in an interview. “It’s like a bad movie. I keep thinking I will be able to change the channel.”

Police said the shooting occurred about 9:40 a.m., when they were called to the single-family home in the 11300 block of Geddys Court, where George Hamilton lived with his mother. Ruth Allen lived a short distance away in the 2000 block of Durand Drive in Reston.

According to George Allen, Marion Hamilton called police after the shooting and emergency workers took his wife to a hospital. The woman, who had recently retired as epidemiologist at the Environmental Protection Agency and had served on the faculty at American University and as an adjunct professor at Yale, died of a wound to the upper body.

Allen remembered his wife of 47 years as a “giving person” who enjoyed working with the Baha’i community in the area. She sang with the Metropolitan D.C. Baha’i Chorale and worked as a life coach. She grew up in Trenton, N.J.

Allen said his brother-in-law served in the Air Force but had not had steady work since leaving in the 1970s. Hamilton had lived with his mother ever since.

“He shot her,” Allen said. “It is unbelievable.”