Investigators have painted a picture of a heavily armed, bearded man massacring two military sites in an attack that left four Marines and the gunman dead. Those who knew him say that doesn't square with the ordinary upbringing they saw.

Muhammad Youssef Abdulazeez died in the attacks, which prompted a gunbattle with police. Neighbors say he was friendly and had been seen dribbling a soccer ball in his yard just days before the killings.

One classmate recalled his sense of humor, evident in a wry quote printed by his yearbook photo. "My name causes national security alerts. What does yours do?"Now investigators are taking a deep look at his online activities and foreign travel, searching for clues to his political contacts or influences.