An Arizona woman was found guilty yesterday by a Prince George's County Circuit Court judge in the beating death four years ago of a 17-month-old Clinton girl, the daughter of her then-boyfriend.

The girl's death initially had been attributed to undetermined causes, but her case was reopened following articles by The Washington Post in 1998 that showed how often child killings are wrongly labeled as deaths from accidents, disease or an unknown cause.

Judge Maureen Lamasney found Gina Louise Vargas, 27, guilty of second-degree murder and child abuse in the death of Nicol Louise Ware, after a two-day trial. The judge said the medical evidence about the injuries Nicol suffered was compelling and convincing.

Prince George's homicide detectives arrested Vargas in Mesa, Ariz., in February, after the death of Nicol was ruled a homicide by D.C. Medical Examiner Jonathan L. Arden. He reopened her case and three unrelated ones after the stories, which detailed how often the true cause of death is missed in young children because of shortcomings in medical, police and social service investigations, and the tendency of families to shield accused relatives.

"I'm very satisfied with the verdict," said Assistant State's Attorney John Maloney.

"This is a good lady who lost her cool," said Gill Cochran, one of Vargas's attorneys.

As the judge announced her verdict, some of Vargas's relatives angrily denounced members of Nicol's family, who were seated on the other side of the courtroom. Sheriff's deputies stepped in quickly to separate the two sides.

Vargas wept softly as the verdict was read.

Vargas could be sentenced to a maximum of 30 years in prison for second-degree murder and 20 years in prison for child abuse. Maloney and Cochran said they believe it is unlikely the judge will impose consecutive sentences when Vargas is sentenced Feb. 25. Vargas testified on Tuesday that in the early morning hours of Nov. 25, 1995, she leaned over and "dropped" Nicol into her padded, three-foot-tall crib. Vargas testified that she dropped Nicol because she was frustrated that the girl would not sit or lie in her crib quietly.

According to trial testimony, Vargas noticed later that Nicol appeared limp, and after talking to her boyfriend's mother on the phone, Vargas called 911. Nicol died two days later at Children's Hospital in the District.

On Tuesday, Steven J. Schiff, a neurosurgeon and professor at George Mason University who cared for Nicol before she died, testified that the girl already was recovering from broken bones in both of her legs and numerous bruises all over her body when she suffered a final, fatal assault.

That final assault left Nicol with a head wound so severe that the right side of her brain turned to mush, Schiff testified. Her injuries were consistent with injuries associated with a high-speed car wreck or a fall from a second-story building, Schiff testified.

When Vargas fatally injured Nicol, she was living with Kevin Ware, Nicol's father. According to testimony, during the time the two lived together, Vargas was the primary caretaker of Nicol and two older boys, who were not injured. Ware, 29, testified that the night Nicol was fatally injured, Vargas told him the little girl had fallen down a flight of stairs by accident.

"I wanted to believe it because I liked her so much," Ware testified.