After a weekend of intense investigation, authorities are piecing together more details about Friday's fatal shooting at Los Angeles International Airport, including the suspect's behavior earlier in the week and a warning from his family that may have come minutes too late. Officers sent to check on Paul Ciancia's welfare arrived at his apartment less than an hour after the shooting started, police said Monday. Here is a rundown to get you up to speed: The suspect Ciancia, 23, of Los Angeles, is charged with murder of a federal officer and commission of violence in an international airport. He was shot by officers Friday and was in critical condition at Ronald Reagan UCLA Medical Center on Sunday. A source said Ciancia was unable to speak to investigators. Clues about a motive Attorney General Eric Holder said Monday that more investigation is necessary to uncover a motive for the attack. But a note found on Ciancia indicated that he wanted to kill Transportation Security Administration employees to instill fear in what the suspect called the agents traitorous minds, FBI Special Agent in Charge David Bowdich said. According to someone who knew Ciancia and his three roommates well, Ciancia began asking for a ride to the airport days before the shooting. He claimed he needed to fly to New Jersey to help his sick father, but he never said what day he needed to leave, the source