After testifying that James Holmes was insane when he committed the 2012 Colorado theater massacre, a defense psychiatrist admitted on Friday that he came to this conclusion before he had reviewed all of Holmes' medical records.

Holmes' defense team opened their case on Thursday, calling Dr. Jonathan Woodcock to the witness stand. According to the psychiatrist, the 27-year-old mass murdered was clinically insane when he opened fire at an Aurora movie theater showing the "Dark Knight" on July 20, 2012. As a result, 12 moviegoers were killed, while 70 others were injured. The former neuroscience graduate student is now on trial for first-degree murder, attempted murder and an explosives offense. If convicted, he will face the death penalty. He, however, has pleaded not guilty by reason of insanity.

According to the defense, the shooter was psychotic and could not tell right from wrong when he intentionally killed people at the movie premiere.

"I was asked to give an initial clinical impression. It was my impression that he was mentally ill. That he was severely mentally ill. And that he had a psychotic mental illness. That is he had an illness which caused considerable disruption in his ability to understand reality," said defense witness Dr. Woodcock, a neurologist and psychiatrist who conducted a mental evaluation of Holmes just days after his arrest, reports CNN.

Woodcock also told jurors that Holmes' psychosis was evident because he was delusional in his thinking and displayed emotional suppression.

"He had this psychosis represented by these delusions and at the same time he was suppressing his emotions so he was not either experiencing or expressing them in a normal way." Woodcock said.

"I knew about the crime and how horrific that was and so that made this mismatch between how he was expressing emotion and what I had heard about what he had done even more remarkable, and led me to the conclusion that this was a very serious disorder."

However, during cross-examination on Friday, Woodcock admitted that he only watched a fraction of hours of interviews, reports Yahoo! News.

District Attorney George Brauchler also pointed out that the jurors had watched more of the 22-hour-long interview than Woodcock.

The prosecution also questioned Woodcock's credibility and expertise in forensic psychiatry.