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:
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 said.
On Friday, Ciancia burst into a roommate's room and demanded a ride to the airport immediately, said the source, who spoke to CNN on the condition of anonymity.
The roommate obliged. Investigators don't think the roommate had any idea of Ciancia's plans.
Around the same time, Ciancia was sending text messages to family members in Pennsville, New Jersey.
One suggested that something bad would happen.
Although Ciancia has no known history of mental illness, he said in the texts that he was unhappy, and the messages were alarming enough that Ciancia's father decided to call police.
"I felt that it was pretty serious. It sounded as if Paul Ciancia in California was thinking about harming himself, so obviously I knew I needed to make a phone call to the LAPD," Pennsville Police Chief Allen Cummings told CNN's Jake Tapper on Monday.
Cummings spoke with a lieutenant there, who told him the department was in the middle of responding to a shooting at LAX.
"At this point, we weren't connecting the dots," he said. They did later when a reporter called the police chief, asking him to comment on the shooting.
Los Angeles Police Department Cmdr. Andy Smith says police were first called to check on Ciancia at 10:06 a.m. Officers arrived at his apartment six minutes later, according to Smith.
Ciancia was already gone.
The timeline provided Monday by police differed from that offered earlier by Rep. Michael McCaul, R-Texas, chairman of the House Homeland Security Committee. He said police had arrived at Ciancia's apartment about 45 minutes after the suspect had left for the airport.
According to the LAPD account, they arrived 52 minutes after the shooting, which began about 9:20 a.m., according to police. It was not immediately clear when Ciancia left for the airport.