VAN NUYS >> A man who allegedly shoved his mother out of a second-story window during an argument at their Van Nuys apartment, then continued to attack her on the ground in front of bystanders, pleaded not guilty Tuesday to a murder charge.

Fernando Vargas, 41, is charged in the Oct. 10 death of his 70-year-old mother, Carlota.

Vargas was allegedly arguing with his mother when he pushed her out of the window about 3 that morning. Vargas then allegedly jumped out of the window and attacked her on the ground outside the apartment building in the 7400 block of Hazeltine Avenue, where they had lived for about a decade.

She died at a nearby hospital.

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A neighbor said she saw Vargas stomping on the woman and was horrified.

“Somebody yelled out for him to stop and he said that she was going to die anyway so that it didn’t matter no more,” the woman said.

Vargas — who was treated for a heel fracture — has remained behind bars since his arrest.

He is due back in a Van Nuys courtroom on Nov. 28, when a date is scheduled to be set for a hearing to determine if there is enough evidence to require him to stand trial.

Vargas faces up to 25 years to life in state prison if convicted as charged, according to the Los Angeles County District Attorney’s Office.