SAN ANTONIO -- A 40-year-old man told a jury Thursday that his sister didn't kill her estranged husband.

"I know she's innocent," Arnold Menchaca said to jurors in the trial of his 50-year-old sister, Beatrix Perez.

The defendant is charged in the beating death of Juan Abitu, 73, in August 2007. Abitu's body was found on the kitchen floor of his North Side apartment.

Menchaca testified that he picked up Perez at the border a month after the slaying. Menchaca said that Perez told him she did not kill Abitu.

"I’m pretty sure she didn't do it," he testified. "I mean that's why I signed the bonds and all that.”

The couple was living apart and were in the process of getting a divorce at the time of the slaying.

Abitu's landlord, Daniel Herrera, testified that he and Perez were having an intimate affair at the time. Herrera said that Perez told him that another woman had called her looking for Abitu and that she was jealous even though she and Abitu were getting a divorce.

The defense is expected to begin presenting evidence Friday.

If Perez is found guilty on a murder charge, she could be sentenced to a maximum sentence of life in prison.