When it comes to prisoners on death row who are insane, the law is very clear: you cannot execute them. The Supreme Court has ruled it unconstitutional and deemed it "cruel and unusual punishment."
But can medication make a prisoner sane enough to be executed? As we first reported last year, that question is being asked in the case of convicted killer Greg Thompson.
As correspondent Lara Logan reports, Thompson was originally found competent to stand trial, but prison doctors have concluded he is mentally ill and they give him medication every day.
Thompson's lawyers are going back to court this fall and will argue that he is still insane on the medication, which he was taking the day 60 Minutes met with him.
Thompson told Logan he had to stab his food to eat it. "Especially eggs. They be popping up," he said. "Hit me in the face. You got to stab it. And then you gotta eat it quick. Real quick."
60 Minutes met Thompson inside a maximum security prison in Nashville.
He has been diagnosed as schizophrenic and psychotic by both prison doctors and those hired by his lawyers. And he has been medicated by the state for most of his 23 years on death row. Thompson receives a daily cocktail of anti-psychotic mood-stabilizing pills, and injections twice a month.
Asked if he knows why he's getting medication, Thompson told Logan, "Yeah, I'm nuts."
He says he only takes 10 pills a day now.
"What happens if you don't take them?" Logan asked.
"I go lulu," Thompson replied.
"Tell me what going lulu is for you," Logan asked.
"In a few days I would like lose my mind and it would be trying to explode on me," he replied. "I got in a fight with the guards a lot of times, you know. Tried to kill a few."
"Did you kill any of them?" Logan asked.
"No," Thompson said. "But at the time they was turning into insects. And I wanted to kill them."
"The guards were turning into insects?" Logan asked.
"Yeah, they were giant insects," Thompson said. "They was acting just like the guards, but they were aliens. And I had to kill the aliens. They were attacking the world."
A psychologist who has been evaluating Thompson for nine years says he sees, hears and smells things that aren't there, and suffers from extreme paranoid delusions and hallucinations.
But when Thompson was put on trial in 1985, his lawyers did not raise insanity as a defense. He confessed, was convicted and sentenced to death for killing Brenda Lane. She was 28 years old, well-liked in her community and she had been married just a few months.
The facts of what happened on New Year's Day in 1985 have never been in dispute. Thompson and his girlfriend, a juvenile, wanted to get from Tennessee to Georgia, so they kidnapped Brenda Lane, stole her car and then drove around for an hour and a half on remote country roads, as Thompson searched for a place to kill her.
They stopped along a rural country road near a field. Thompson then stabbed Brenda four times in the back and drove off, leaving her to die alone in the cold and the dark.