NEWTOWN, Conn. (AP) — The massacre of 26 children and adults at a Connecticut elementary school elicited horror and soul-searching around the world even as it raised more basic questions about why the gunman, a 20-year-old described as brilliant but remote, was driven to such a crime and how he chose his victims.Investigators were trying to learn more about Adam Lanza and questioned his older brother, who is not believed to have been involved in the rampage at Sandy Hook Elementary. Police shed no light on the motive for the second deadliest school shooting in U.S. history.Lanza is believed to have suffered from a personality disorder and lived with his mother, said a law enforcement official who was briefed on the investigation.Asked at a news conference whether Lanza had left any emails or other writings that might explain the rampage, state police Lt. Paul Vance said investigators had found “very good evidence” and hoped it would answer questions about the gunman’s motives. Vance would not elaborate.The tragedy plunged the picturesque New England town of 27,000 people into mourning.“People in my neighborhood are feeling guilty about it being Christmas.