SAN ANTONIO -

Though his brother Richard Mendez, 25, has pleaded guilty to stabbing Gary Cooper, 25, to death in the summer of 2011, his brother, Jacob Gonzalez, 24, is on trial in connection with the slaying.

Gonzalez is charged with murder under the law of parties since he aided and encouraged the murder, according to prosecutors.

Cooper was stabbed to death after the brothers broke into the South Side apartment of Mendez’s estranged wife, Ashley Mendez.

She testified on Wednesday that she was Cooper’s girlfriend at the time.

San Antonio police Officer Edwin Bello was the first officer on the scene the night of July 7, 2011.

“He was bleeding -- the front of his clothes was full of blood,” Bello testified as he explained how he saw Cooper stagger down the stairwell outside Mendez’s apartment. “He leaned against the truck or vehicle that was parked right there on the bottom floor and proceeded to fall to the ground."

Cooper was stabbed in the heart.

Richard Mendez plead guilty to the murder last February and is serving a 45-year prison term.

If he is convicted, Gonzalez faces a maximum sentence of life in prison.

Testimony will continue on Friday in 144th District Court with Senior Judge Pat Priest presiding.