(CNN) -- 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 moments too late. Here is a rundown to get you up to speed: THE SUSPECT Paul 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 Sunday. A source said Ciancia was unable to speak to investigators.
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Suspect Paul Ciancia, 23, is in critical condition and could face the death penalty
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Wife of slain TSA officer Gerardo Hernandez, 39, says her husband "took pride in his duty"
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Police, responding to family concern, arrived at Ciancia's apartment shortly after he left for airport
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The TSA chief says security protocol is under review
According to someone who knew Ciancia and his three roommates well, @placeholder began asking for a ride to the airport days before the shooting.