A Lehigh County jury must determine if an Allentown man is guilty of fatally shooting a boy and his grandmother more than two years ago in the city.

Gabriel Cartagena’s trial in the Dec. 29, 2023, killings of Ada Ortiz, 44, and her grandson, Sebastian Serrano, 1, began Tuesday in Lehigh County Court. Cartagena, 45, is also charged with shooting Ortiz’s husband, Leandro Ortiz, who survived his injuries.

City police said Ada Ortiz and Sebastian were shot in a home in the 100 block of Chestnut Street that night. Leandro Ortiz was shot while trying to prevent one of his other grandchildren from getting shot, according to authorities. They were with three of their grandchildren at the time.

Ortiz testified during Cartagena’s preliminary hearing nearly two years ago that he heard a knock at the door. Ada Ortiz opened the door, and Cartagena shot her and Sebastian with a semiautomatic handgun before trying to shoot one of the other grandchildren, according to testimony. Leandro Ortiz pushed him out of the house, and was shot in the process, he testified. Ada Ortiz and Sebastian died at the home.

During the second day of trial Wednesday, Allentown Detective Theodore Kiskeravage, who filed the charges, testified that he took a DNA swab from Cartagena about two months after the killings. That DNA was tested against evidence at the scene, including a cigarette butt, which authorities have said Cartagena left while fleeing the scene.

Tyeisha Moore, a forensic biologist with the Bureau of Alcohol, Tobacco, Firearms and Explosives, testified that Cartagena’s DNA was found on the cigarette butt, along with at least one other person’s who was not identified.

Cartagena’s public defender, Kathryn Smith, asked if there were any way to determine when Cartagena touched it, or how his DNA got on the cigarette. Moore said her testing could not reveal that information.

Authorities have not said what motive there was for the shootings, and Leandro Ortiz said he never saw Cartagena before that night.

The trial is expected to continue through the week. Cartagena remains in Lehigh County Jail without bail.