"He kept to himself and ate lunch alone a lot," David Hamilton told the Los Angeles Times. "I really don't remember any one person who was close to him .... In four years, I never heard a word out of his mouth."
On Friday, Ciancia's father called police in New Jersey, worried about his son in L.A. The young man had sent texts to his family that suggested he might be in trouble, at one point even saying goodbye.
The call came too late. Ten minutes earlier, police said, he had walked into the airport.
In the worrisome messages, the younger Ciancia did not mention suicide or hurting others, but his father had heard from a friend that his son may have had a gun, said Allen Cummings, police chief in Pennsville, a small blue-collar town near the Delaware River where Ciancia grew up.
The police chief called Los Angeles police, who sent a patrol car to Ciancia's apartment. There, two roommates said that they had seen him a day earlier and he had appeared to be fine.
But by that time, shots were already breaking out at the airport.
"There's nothing we could do to stop him," Cummings said.
The police chief said he learned from Ciancia's father that the young man had attended a technical school in Florida, then moved to Los Angeles in 2012 hoping to get a job as a motorcycle mechanic. He was having trouble finding work.
Ciancia graduated in December 2011 from Motorcycle Mechanics Institute in Orlando, Fla., said Tina Miller, a spokeswoman for Universal Technical Institute, the Scottsdale, Ariz., company that runs the school.
A basic motorcycle mechanic course takes about a year, she said.
On Friday, as swarms of passengers dropped to the ground or ran for their lives, the gunman seemed to ignore anyone except TSA targets.
Leon Saryan of Milwaukee had just passed through security and was looking for a place to put his shoes and belt back on when he heard gunfire. He managed to hide in a store. As he was cowering in the corner, the shooter approached.
"He looked at me and asked, 'TSA?' I shook my head no, and he continued on down toward the gate," Saryan said.
Authorities identified the dead TSA officer as Gerardo I. Hernandez, 39, the first official in the agency's 12-year history to be killed in the line of duty.
Friends remembered him as a doting father and a good neighbor who went door-to-door warning neighbors to be careful after his home was burglarized.
In brief remarks outside the couple's house, his widow, Ana Hernandez, said Saturday that her husband came to the U.S. from El Salvador at age 15.
"He took pride in his duty for the American public and for the TSA mission," she said.Associated Press writers Gillian Flaccus and Alicia Chang in Los Angeles and Geoff Mulvihill in New Jersey contributed to this report.