MIAMI -

A teenager accused of killing a man and his girlfriend at a Miami Gardens gas station fatally shot the couple because one of the victims did not look scared enough, assistant state attorney Alejandra Lopez told jurors on the opening day of his murder trial.

Eric Ellington is on trial in the July 2011 shooting that claimed the lives of Julian Soler, 23, and Kennia Duran, 24. Ellington was 16 at the time.

Surveillance video shows the couple stopping to put gas in Soler's Ford Mustang. An SUV then pulls up, and a gunman is seen forcing Soler out of the car before shooting the couple.

Soler died at the scene. Duran was pronounced dead at a hospital.

During her opening statements Wednesday, Lopez said Ellington, who is now 19, and his accomplices had just committed another gas station robbery.

After showing jurors the surveillance video, she then presented what she said was the motive for Ellington to kill the couple.

"(Soler) didn't look scared enough," she said.

Lopez then stated how Ellington carried out his crime.

"That man shoots him -- not once, not twice, but eight times," Lopez told jurors.

Ellington's attorney said his client was intimidated by police into a confession with his mother present. He hinted that he would discredit physical evidence.

"That video does not give you the certainty that you need," attorney Herbert Smith said.

Smith told jurors they will be angry and want justice.

“But you cannot let it affect your assignment of legal guilt, of legal responsibility," Smith said.

Before the trial began, the state offered Ellington a plea deal: 40 years in prison in exchange for his testimony against the other suspects. Ellington rejected the offer.

Ellington faces several charges, including two counts of first-degree murder, armed carjacking and armed robbery.