In graphic animated testimony, Richard Mendez described how he and Gary Cooper struggled inside his apartment on the night of July 7, 2011.

He and his brother, Jacob Gonzalez, had surprised Cooper, who was inside the apartment with Mendez’s estranged wife Ashley.

During the fight, he said, Cooper pulled a knife.

“Right when he had it in his hand, he swung at me straight with a stabbing motion,” Mendez testified.

He said that as they fought, Cooper lost his balance.

“He fell holding onto the knife?” asked defense attorney Paul Smith.

“Yes sir,” Mendez replied.

“And where did the knife go in?” Smith asked.

“About this area -- about an inch below the nipple,” Mendez said, gesturing toward his chest.

He said his brother was not part of that fight. He said Gonzalez only pushed his way past Cooper on his way to an adjacent bedroom to check on Mendez’s three children.

Mendez pleaded guilty to Cooper’s murder last year and is serving a 45-year prison term.

Gonzalez is also charged with murder under the law of parties. Prosecutors allege that he “aided and encouraged” the slaying.

If he is found guilty, Gonzalez is facing a maximum sentence of life in prison.

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

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