A new videotaped confession was played Monday in the Etan Patz murder trial from accused killer Pedro Hernandez.
It's the fourth in the trial so far and was made to a psychiatrist working for the prosecution.
"And whatever happened there, I choke him. It was something that just happened quick. I don't know why I did it," Hernandez says in the video.
Dr. Michael Welner spent 18 hours talking with the accused on video, 20 months after prosecutors charged him with kidnapping and killing the six-year-old.
He testified Hernandez does not have a serious mental illness, and didn't appear to have one on the day Patz vanished in 1979.
The defense says Hernandez hallucinated that he strangled Etan -- and then believed it.
That's why the defense says he told at least five people he killed the boy.
Defense witnesses have said Hernandez's low IQ made him an easy target for a forced confession, but the prosecution's witness says false confessions are very rare.
During one session, he found Hernandez has at least some math skills.
Welner: "If you have $20 in commissary and you buy a bag of chips, what would you have left in the commissary?"
Hernandez: "$19.55."
The defense argues that another man, Jose Ramos, could have committed the crime.
The family sued the convicted pedophile years ago and a judge found he was liable—but there was never enough evidence to bring criminal charges.
The jury could get the case this week.