NEW YORK (CBSNewYork/AP) — A defense psychologist on Tuesday the man who admitted killing a 6-year-old New York City boy who went missing 35 years ago did not understand his right to silence.

Bruce Frumkin said Tuesday that Pedro Hernandez was tested for several hours, and believes Hernandez would not have fully understood what he was agreeing to when he said he understood his Miranda rights.

A judge is weighing whether to allow the videotaped confession by Hernandez, who admitted choking Etan and dumping his body. The boy vanished walking to school on May 25, 1979. His body was never found.

Hernandez was arrested in connection with the case in 2012, and has pleaded not guilty.

Prosecutors sought to show that Frumkin’s opinion was faulty. Assistant District Attorney Joan Illuzzi-Orbon read jailhouse calls where Hernandez said he could not see during the psychiatric test because he didn’t have his glasses.

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