William Lowery was asleep on his living room couch in front of the television set when a scream from the basement recreation room of his house in Cheverly shook him awake just before 1 a.m. Saturday.

"I no sooner heard her scream and started to move than I hear 'pop, pop . . . pop, pop, pop.' I heard two, and then three," said Lowery. "I ran downstairs and Kathy's lying on her stomach across the bed.

" 'Help me, Daddy,' she says. 'Help Jessie.' "

Lowery's son-in-law, James Harold Jerew Jr., 21, lay in a heap of clothes, dead from an apparently self-inflicted gunshot wound to his head. In his hand was a revolver he had apparently used to shoot his wife, Kathleen Mary Jerew, 20, and their son, Jessie, 2, before shooting himself.

Lowery rushed his grandson to Prince George's General Hospital. Kathleen was taken to the hospital by ambulance. Two hours later, the boy and his mother were dead.

Prince George's police yesterday listed the deaths at 3418 Cheverly Ave. as a double homicide and apparent suicide. They, as well as the Lowerys, were still trying to piece together the events that led to the deaths of the two young suburban Marylanders and the child they had named Jessie James.

"I don't know what happened," said Lowery outside the small brick house where the shootings took place. "I don't have any idea."

Before the sudden violence, the Lowerys had been a family drawn together by lean economic times, the father letting his daughter and her husband share his house until they could make it on their own.

Kathleen Lowery and James Jerew had grown up not far from each other in the suburbs near the District line. They met through friends when they were teen-agers, while he was on leave from the Army. Kathleen Lowery was 17 when they married, Jerew a year older.

As a civilian, Jerew took a job as a painter at the Lowery family painting business, Shield Inc., on Annapolis Boulevard. The young couple rented an apartment not far away, and soon thereafter Jessie James Jerew was born.

For two years, Jerew painted for William Lowery. "He was a good and steady worker," Lowery said. "But he didn't have a lot of experience. He wasn't what you'd call a hustler."

Jerew got tired of painting, Lowery said, and decided to draw on his Veterans Administration benefits and enroll in mechanics school at the Diesel Institute of America in Landover. Jerew's income dropped dramatically when he left the painting job.

"They were having trouble making ends meet," Lowery said. "There wasn't enough to pay rent, the way it is now. I figured I'd help 'em out, let 'em live here free." So the Jerews moved into the Lowery's finished basement recreation room. They had a bed for themselves and next to that a toddler's bed for Jessie.

Jerew's classes at the Diesel Institute normally let out at 1 p.m. On Friday morning, a friend who was a classmate called Kathleen Jerew at home, saying that "Sonny," as her husband was called, had left classes early. He had been "acting funny," the friend said. Kathleen Jerew spent the rest of the afternoon in the family car searching for her husband in the bars and pizza joints where she knew he liked to go, Lowery said. About 5 p.m., Jerew came home.

"I said, 'What's wrong?' " Lowery recalled. "He said, 'Nothin. I just ain't feelin' good.' I said, 'Sonny, you only got a couple weeks to go [with school]. You're gonna mess up the whole damn thing.' He said, 'I'm not gonna mess up no more.' "

That evening, James and Kathleen Jerew and her brother, Billy, and his girlfriend drove to the Mama Lucia Pizza Parlor in the Cherry Hill Shopping Center for dinner. When they came home, they watched television in the living room with the family. Jerew went downstairs to bed early. About 10:30, his wife joined him.

"He was quite all right," said Lowery. "We never had any fights. Nothing." Lowery had fallen asleep on the couch and his wife had gone to bed when the shots that they still cannot explain jolted them awake.