He admitted that he shot the mother of his three young children to death just over three years ago. But Marcus Robinson. 24, did not offer a motive.

When Robinson’s trial began, he refused to enter a plea, so his lawyer entered a not guilty plea on his behalf.

Jasmine Whipple, 21, was shot in the back and the head outside the home of Robinson’s grandmother, Melrose Goode, on the evening of Nov. 10, 2010.

“The defendant had gotten angry and got a shotgun from the trunk of his car and shot her in the back,” prosecutor Lorina Rummel told the jury during opening arguments.

Goode testified that after the shooting, her grandson admitted killing his girlfriend and the mother of his three children.

“What did Marcus tell you about how she received her gun wounds?” Rummel asked Goode.

“He just said he shot her,” Goode answered.

Robinson also admitted to police that he shot Whipple.

But he did not offer a motive to police or to his grandmother.

Testimony will continue on Wednesday in Judge Ron Rangel’s 379th District Court.

If he is convicted, Robinson is facing a maximum sentence of life in prison.

For a list of recent stories Paul Venema has done, click here.