HOUSTON -- Attorneys are trying to convince a jury to spare the life of an illegal immigrant found guilty of killing a Houston police officer, KPRC Local 2 reported Tuesday.

Juan Leonardo Quintero, 33, was found guilty of capital murder in the death of Officer Rodney Johnson. Quintero was in the back seat of Johnson's patrol car after he was arrested for driving without a license on Sept. 21, 2006.

Prosecutors are seeking the death penalty. They have to prove to the jury that Quintero presents a future danger to society to warrant that punishment.

Quintero may testify in the punishment phase of the trial. Attorneys said they want the jury to know he feels remorse.

He pleaded not guilty by reason of insanity, claiming that a childhood brain injury caused him to not be able to reasonably react to some circumstances.

Quintero confessed to the murder, but said he shot Johnson because he was afraid of being arrested and the possibility that he could be deported to Mexico because he was in the United States illegally.

Testimony in the punishment phase is expected to last about three days.