[Breaking news update, published at 6:52 p.m. ET]
The suspected Fort Lauderdale airport shooter has been charged with three federal charges that each carry the possibility of the death penalty, the US Department of Justice said Saturday. Esteban Santiago faces charges of performing an act of violence against a person at an airport serving international civil aviation that caused serious bodily injury; using and carrying a firearm during and in relation to a crime of violence; and causing the death of a person through the use of a firearm.
[Breaking news update, published at 1:25 p.m. ET]
Investigators believe the suspect in the fatal Fort Lauderdale airport shooting had been planning to carry out his attack for some time, law enforcement officials tell CNN. Accused shooter Esteban Santiago recently began selling his possessions, including his car, and friends and associates noticed more erratic behavior, investigators have learned from interviews with those who know him. Authorities are examining writings, including online posts, that in retrospect appear to indicate some period of planning, law enforcement officials say.
[Previous story, published at 12:52 p.m. PT]
The suspected gunman who opened fire at the Fort Lauderdale airport "came here specifically to carry out this horrific attack," Miami FBI Special Agent George Piro said Saturday.
"We have not identified any triggers that would have caused this attack," he added.
Esteban Santiago, the suspected attacker, went to baggage claim Friday afternoon to pick up his one piece of checked luggage: a case with a handgun inside, authorities said.
Santiago allegedly took the 9 mm handgun out of its case and fired at other travelers Friday afternoon, killing five people at the Fort Lauderdale airport. On Saturday, authorities revised the number of wounded to six after earlier saying eight.
A few months earlier Santiago reportedly had a mental evaluation after a bizarre visit to an FBI office in Alaska.
Friday's shooting sent the airport terminal into chaos, with people scurrying for cover. They started running again when rumors of more gunshots and a possible second shooter spread through the busy airport. Almost 40 others would get hurt in the rushed evacuation after the attack. Some suffered sprains and bruises; others had broken bones.
Here's what we know about the deadly shooting and what officials have said about the suspect:
Who is Esteban Santiago?
Law enforcement officials identified Esteban Santiago, 26, as the suspect in the five deaths at Fort Lauderdale-Hollywood International Airport.
Santiago didn't resist when he was taken into custody, Broward County Sheriff Scott Israel said. According to his booking information, Santiago is being held without bond on a murder charge.
He lives in Alaska, where he was a security guard.
Alaska was also the site of his last military assignment. He was a member of the Alaska Army National Guard from November 2014 until August when he was discharged for unsatisfactory performance, a spokeswoman for the guard said.
In November, Santiago paid a visit to the FBI office in Anchorage, telling agents he was hearing voices and being directed by a US intelligence agency to watch ISIS videos, law enforcement sources told CNN.
George Piro, the FBI's special agent in charge in Miami, told reporters that Santiago was turned over to local authorities and he voluntarily submitted to a mental health evaluation.
"His erratic behavior concerned FBI agents," Piro said Saturday.
Santiago was armed during his visit to the FBI office, law enforcement officials told CNN. He told federal agents he was licensed to carry a gun. As was standard practice in a FBI building, authorities took the gun and turned it over to local police.
Investigators believe it was the same gun that was found at the scene of Friday's shooting.
In January 2016, Santiago was arrested and charged with assault and criminal mischief after an argument with his girlfriend in Anchorage, Alaska, according to court documents that CNN obtained.
At the time, Santiago allegedly yelled at his girlfriend while she was in the bathroom, according to the complaint. He then broke down the bathroom door.
The woman told investigators that Santiago strangled her and struck her in the side of the head, the complaint said. Santiago left before police arrived.
Anchorage municipal prosecutor Seneca Theno said Santiago pleaded no contest to criminal mischief and assault charges. Under a deferred prosecution agreement, the charges would have been dismissed if he complied with the conditions. He was due back in court on March 28.
The military said Santiago's nine years of service in the National Guard included one 10-month tour of Iraq, where he was awarded a combat action badge.
Santiago returned from Iraq a changed man, his aunt told CNN on Saturday.
"His mind was not right," the aunt, Maria Ruiz Rivera, said in a phone interview in Spanish from her home in New Jersey. "He seemed normal at times, but other times he seemed lost. He changed."
She added, "He talked about all the destruction and the killing of children. He had visions all the time."
Ruiz said she lost contact with Santiago several months ago.
"He stopped calling," she said. "He wouldn't respond to my messages. I would call and text. He seemed distant."
Her family is still in shock.
"Who would have imagined that he could do something like this?" she said. "I don't say that because we're family. I say it because he wasn't like that."
The suspect's brother, Bryan Santiago, said he believes the shooting rampage resulted from mental issues that surfaced after the Iraq tour.
Esteban Santiago requested medical help from army and federal agencies, according to his brother. He received some treatment.
Bryan Santiago, in an interview in Peñuelas, Puerto Rico, said he used to speak with his brother regularly but the communication ceased about a month ago.
How did he get to Fort Lauderdale?
Piro said Santiago flew from Anchorage to Minneapolis to Fort Lauderdale on a Delta Air Lines flight.
A lieutenant with the Anchorage airport police said Santiago had one bag -- a handgun case with a pistol inside that he checked.
Authorities do not know why Santiago was in Fort Lauderdale.
But Piro said Saturday that Santiago "came here specifically to carry out this horrific attack."
"We have not identified any triggers that would have caused this attack," he said.
Piro said investigators were looking at airport video to see how the rampage unfolded. Authorities have conducted more than 100 interviews as part of their investigation.
What was the motive?
The FBI has not ruled out terrorism, Piro said, but Israel cautioned it was early in the investigation and authorities did not know Santiago's motive.
On Saturday, Piro said investigators "continue to look at the terrorism angle" as a possible motive.
"We have not ruled out anything," he said. "We continue to look at all avenues, all motives."
Piro said Santiago was cooperating with investigators, who had interviewed him for several hours. The interview concluded early Saturday.
There were reports of a possible altercation involving Santiago on the flight to Fort Lauderdale, but law enforcement sources said investigators haven't discovered any evidence to support those claims.
The airline said it had received no reports of any incidents during the flight.
"Reports from customers and crew onboard the flight in question indicate that there was not a customer altercation during the flight," according to a Delta representative.
Terry Andres of Virginia Beach, Virginia, was at the airport to begin a vacation with his wife, Ann, and a celebration for the couple -- his 63rd birthday was coming up, according to a close friend.
Andres died; his wife was uninjured, said the friend, who asked to remain anonymous.
"Terry was the kindest, sweetest and best kind of friend anyone could have. He was the ultimate family man," said the friend, who has known Andres since high school. "He and Ann were married for 40 years, and he absolutely adored his children and grandchildren."
Another victim was Olga Woltering, 84, who was traveling with her husband, Ralph. They were on their way from their home outside Atlanta for a cruise.
The great-grandmother and loyal church member died; her husband escaped serious injury, according to posts on social media.
"Olga was one of the most joyful, loving, caring and committed people I have ever met," the Rev. Fernando Molina-Restrepo of the Catholic Church of the Transfiguration in Marietta, Georgia, told CNN. The Wolterings had been members of the church since 1978, the priest said.
What was it like at the airport?
Sara Graham, who had been vacationing in Fort Lauderdale, wrote on Instagram that she and her family were about 100 feet away from the shooter.
Graham said her brother led her and her mother to safety after the commotion began.
"When we first heard the shots we had no idea what was happening until everyone started running towards exits," she wrote. "We hid for about 30 minutes and we're let back inside, under the impression it was all safe."
Then there was a rumor of another shooter and people started running again.
"Once we were outside, we had to run three more times until we were sure that we were safe," she said.
They spent the rest of Friday afternoon in an aircraft hangar before people were allowed to leave.
One man told CNN's Anderson Cooper that a laptop in a backpack he had slung over his shoulder stopped a bullet that could have killed him.
"I felt something hit my back," Steve Frappier said, adding he thought it was luggage falling off the carousel.
It was a bullet, which ricocheted off the laptop. He found it in the side pocket of his bag.
Other witnesses described the aftermath of the shooting as a "war zone" and "mass hysteria."
What are rules for firearms in airports/checked bags?
Taking a gun on a plane is legal if a passenger brings the weapon in a case that locks and checks the suitcase containing the gun.
The gun cannot be loaded, though regulations allow travelers who fill out a declaration form to also bring ammunition.
Florida law prohibits guns inside terminals unless they are still in their case, but there is a bill before the state Legislature to allow guns in public places such as airports.
How was air traffic affected?
The Fort Lauderdale airport was closed for the rest of Friday, and more than 10,000 travelers had their trips interrupted for hours.
Flight tracking website FlightAware said 159 arrivals and 149 departures were canceled -- about a third of the scheduled flights.
The airport reopened Saturday.
By Saturday afternoon, planes had begun to depart from Terminal 2 for the first time since the shooting. The baggage claim at Terminal 2, where the shooting occurred, remained closed.
Passengers were advised to check with their airline before traveling.
The airport said earlier it was collecting and processing more than 20,000 bags and personal items left behind during the evacuation to return them to their owners.