“All he did was play video games and play music,” said Tommy Marriotti, a high school friend. Mr. Marriotti said much of Mr. Loughner’s free time was devoted to the school band. He wasn’t especially political, Mr. Marriotti said, though he expressed frustration with the Bush Administration…

Mr. Montanaro said his friend “was never really political,” but “really tried to be philosophical.” Mr. Loughner liked “contemplating the meaning of words and the origin of language,” Mr. Montanaro said.

That interest might have triggered Mr. Loughner’s first meeting with Ms. Giffords in 2007. Mr. Loughner said he asked the lawmaker, “How do you know words mean anything?” recalled Mr. Montanaro. He said Mr. Loughner was “aggravated” when Ms. Giffords, after pausing for a couple of seconds, “responded to him in Spanish and moved on with the meeting.”