Karrer said there were about 500 kids at Castroville Elementary when the gunman was in 5th grade.
Karrer identifies class photo of the gunman in 5th grade.
Karrer said the gunman was the "cohort" or leader in a group of 5-6 kids that were far above average academically.
Karrer said about the group of gifted students: "It was a pleasant rivalry... very unusual, which is why I remember it."
Karrer on the gunman: "He smiled. He was a smiler... the kids liked him a lot. There was no dark side."
Karrer said the gunman and his friend suggested building a website: "They did the coding... I didn't know what the heck they were doing."
Dr. Gur testified that the gunman first showed signs of self-destructive behavior after the family moved in 6th grade.
Karrer on gunman in 5th grade: "He was balanced. He had it all. He was like a Renaissance child... the kids liked him."