"The way the text message was phrased to his sister, I'm not sure she would have taken it as anything. I think only when you look at it in retrospect does it really have the impact that it does now," Flaiz said.
Lane's sister, Sadie, was in the cafeteria the day of the shooting, and said outside the snow-swept courthouse that the brother she saw in court wasn't the one she remembers. She asked for prayers for her family.
"It may be hard for some to understand, but I love my brother and hope that whatever the sentencing in life takes him in the future, that he can touch others' lives in a positive way from the point of view that only he can give," she said.
She spoke and left the courthouse before Flaiz addressed reporters.
Flaiz said he has a theory about the motive but wouldn't discuss it until he has a chance to meet with the families of victims and answer their questions.
Lane's courtroom behavior came as a surprise, he added.
"I am totally disgusted by that," Flaiz said. "What he did today is consistent with what we thought of him all along."
One of Lane's defense attorneys, Ian Friedman, also said he was caught off-guard by the comments. The defense had signaled earlier that Lane wouldn't speak in court and didn't want anyone to speak for him.
Lane had pleaded guilty last month to three counts of aggravated murder, two counts of attempted aggravated murder and one count of felonious assault.
Life imprisonment without parole was the maximum sentence Lane faced. He wasn't eligible for the death penalty because he was 17 at the time of the shootings. Relatives of the slain students indicated earlier they wanted Lane to get the maximum sentence.
In addition to three life sentences without chance of parole, Geauga County Common Pleas Judge David Fuhry also gave Lane sentences totaling 37 additional years for attempted murder and felonious assault and using a weapon in the crimes.
Associated Press freelance reporter John Coyne contributed to this report.