THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.
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 was 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.
A law enforcement official speaking on condition of anonymity said investigators believe Lanza attended the school several years ago but appeared to have no recent connection to it. It was not clear whether he held a job.
At least one parent said Lanza's mother was a substitute teacher at the school. But her name did not appear on a staff list. And the official said investigators were unable to establish any connection so far between her and the school.
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