ORLANDO, Fla. -- The gruesome, chilling details of the way eighth-grader Jaime Gough was killed in his middle school bathroom unfolded on Thursday for a jury of six men and six women in Orange County, as prosecutors opened their first-degree murder case against Jaime’s then-classmate, Michael Hernandez.

“He encircled Jaime with his left arm, lifted his chin and slit his throat,” prosecutor Carin Kahgan told a rapt jury. “Jaime turned to him and said, 'Please, don’t kill me and he said he wouldn’t and he said ‘I lied’.”

Kahgan read portions of a transcript from a confession Hernandez gave Miami-Dade homicide Det. Sam Garafolo the day of the killing, Feb. 3, 2004.

She outlined evidence the jury will see of how Hernandez carefully planned the killing, bringing gloves and a knife in a backpack to school, luring Jaime into the school before the first bell, into a bathroom stall under the guise of showing him a surprise.

Hernandez is also charged with attempted murder, for trying to lure in and kill another classmate a day earlier, but that boy refused to go.

For a first-degree murder conviction, prosecutors must prove Hernandez planned the killing and carried it out.

In opening statements for the defense, Hernandez’s attorney told the jury he will prove Hernandez was insane at the time of the crime, and therefore should not be held responsible for his actions.

''This is a classic case of insanity. This is not a farce. This is not an excuse. This is not a normal child,'' Rosenbaum told the jury. “What kind of 13 or 14-year-old makes it their life’s mission to become a serial killer?”

Local 10 Exclusive With Michael Hernandez's Mom

Michael’s mother, who was in the courtroom for the 3 -day jury selection, is on the witness list and so may not watch or listen to the trial proceedings until she testifies. She spoke with Local 10 from the living room where she is staying in Orlando.

“Wouldn’t it be nice if I was sitting there watching him be an attorney instead of what he’s going through,” she said tearfully. “I just hope people understand he is mentally ill. Any parent would feel a loss if they found out their child is mentally ill, and to have this horrific thing on top of it is just unbearable.”

If Michael is found not guilty by reason of insanity, he will likely get mental health treatment. If he is found guilty, he will be sent to prison for life.

His mother is certain that Michael, at age 18, can be helped.

“He may spend years and years and years in a mental institution, I don’t know, but at least he’d be in the right place. You don’t get the help you need in the prison system,” she said.

“I would never ask the Gough’s to forgive Michael but what I do hope is that at some point in time that they will have some understanding that he’s sick, very, very sick. And he’s not a horrible person and there was a reason their son was friends with Michael. And that’s the Michael I wish they could have known.“