Getting your Trinity Audio player ready...

A Cook County jury has been asked to decide a most unusual issue: Is a defendant who is charged in the killing of off-duty Chicago police Officer Thomas Wortham IV mentally unfit to stand trial because he can’t remember any details from the incident?

Marcus Floyd, wounded in a shootout with Wortham and the officer’s father, suffered “retrograde amnesia” when his brain was deprived of oxygen after losing massive amounts of blood, his attorneys contended Tuesday. He also suffered two heart attacks and spent a week in a coma, they said.

“He can’t assist in his defense because he doesn’t know what his defense is,” said David McMahon, an assistant public defender. “He will never, ever recover those memories, and based on that, he’s not fit to stand trial.”

But prosecutors told jurors that Floyd, now 24, meets the legal definition of mental fitness because he can make new memories, speak coherently and logically, and assist his attorneys in his trial. No test exists to prove whether Floyd does or does not have amnesia, they said.

“You don’t have a person who is catatonic, you don’t have a person who is having hallucinations, you don’t have a person who can’t sit there and talk with counsel and assist during trial,” said Assistant State’s Attorney Mike Deno.

A six-person jury and two alternates have been picked to decide a legal issue usually left to a judge. If the jury finds Floyd mentally fit, he would later go to trial. But if the jury finds him unfit, Judge Timothy Joyce would decide the next step.

Wortham’s family — his parents and sister — attended Tuesday’s proceedings at the Leighton Criminal Court Building. Floyd leaned forward in his seat, his head resting in his hands, appearing to sleep at least once.

Prosecutors have alleged that Wortham was fatally shot in 2010 as four men attempted to rob him of his new motorcycle in front of his parents’ home in the Chatham neighborhood. When Floyd and his cousin confronted Wortham, the off-duty officer drew his gun, identified he was a cop and exchanged gunfire, according to testimony at his trial.

Wortham’s father, Thomas III, a retired Chicago police sergeant, retrieved his service weapon and joined in the shootout. Floyd was severely wounded and his cousin Brian Floyd was killed.

In dramatic testimony, the elder Wortham said that as he engaged in a shootout with the cousins, Paris McGee fired a shot at him from the fleeing getaway car. The elder Wortham said he grabbed his son’s gun from the ground and fired both weapons at the car. Toyious Taylor, driving the car, struck Wortham’s fallen son and dragged the body about a quarter of a mile down the street, he said.

McGee and Taylor were convicted and sentenced in February to mandatory life sentences.

The younger Wortham, 30, a three-year police veteran, had returned home a month earlier from a second tour of duty in Iraq with the Army.

A true amnesia defense is rare, according to testimony Tuesday from experts who have evaluated thousands of Cook County defendants.

Floyd, who lost four liters of blood and his right kidney after being shot at least five times, spent months recovering in three hospitals. He said he last remembers watching TV with his girlfriend while his daughter played with toys sometime before the shooting.

He next remembers waking up in a hospital bed with an NBA playoff game on the TV, according to testimony.

“It’s like a dream, like a trance,” Floyd allegedly told a forensic psychiatrist.

But experts testifying for the prosecution said Floyd was able to make new memories, remembering in detail everything from the jailhouse menu to the outcomes of NBA games, and reciting his 11-digit booking number during an evaluation.

Floyd also continues to function at a fairly high level, reading a Sister Souljah-penned novel, said Christofer Cooper, a forensic psychologist, who concluded Floyd was fit to stand trial.

“Despite the very serious, life-threatening injuries he suffered, he has fully recovered intellectually and cognitively,” Cooper testified.

Dr. Mathew Markos, another forensic psychiatrist testifying for the prosecution, agreed that Floyd was mentally fit to stand trial.

“Amnesia per se does not equal unfitness,” he said.

The hearing is scheduled to continue Wednesday.

[email protected]

Twitter @SteveSchmadeke