U.S. prosecutors have charged the man suspected of carrying out a deadly shooting at a Florida airport.
Esteban Santiago, 26, is accused of fatally shooting five people and wounding six others at a Fort Lauderdale-Hollywood International Airport baggage claim on January 6.
Prosecutors said on January 7 that the suspect was charged with firearms offenses and carrying out an act of violence at an international airport resulting in death, which carries a maximum punishment of execution.
Santiago, who is in custody, told agents he had planned the attack and bought a one-way ticket to Fort Lauderdale, according to court papers.
Investigators are probing whether mental illness played a role in the attack.
The FBI said terrorism had not been ruled out as a possible motive of the shooting.
Reports said Santiago, who served in Iraq in 2010-11, was discharged from the National Guard last year after being demoted for unsatisfactory performance.
In November, he walked into an FBI field office in Alaska complaining that his mind was being controlled by national intelligence agencies, which were forcing him to watch Islamic State videos, authorities said.
Santiago was carrying a loaded magazine but had left a gun in his vehicle, along with his newborn child, police said.
Officers confiscated the weapon and took Santiago to get a mental-health evaluation, but the gun was returned to him in December.
It was unclear whether it was the same weapon used in the airport attack.
Santiago's brother said he had told him in August that he was hearing voices and felt he was being chased.
"How is it possible that the federal government knows, they hospitalize him for only four days, and then give him his weapon back?" Bryan Santiago asked.
Santiago is expected to make his first appearance in court on January 9.
He is said to have used a semiautomatic handgun that he appears to have legally checked on a flight from Alaska.
It is legal for airline passengers to travel with guns and ammunition as long as the firearms are kept in a locked, hard-sided container as checked baggage.