(CNN) -- A federal grand jury on Thursday indicted Esteban Santiago, the man accused of killing five people inside a Fort Lauderdale airport this month, authorities said.
Santiago is charged with numerous counts and could face death or life in prison.
Federal authorities said Santiago, 26, wounded six others when he opened fire in the baggage claim area of the Fort Lauderdale-Hollywood International Airport, aiming at victims' heads and bodies until he ran out of ammunition.
Santiago was confronted by a Broward County Sheriff's deputy and dropped his weapon.
Santiago, who lived in Alaska, told FBI agents he carried out the January 6 attack on behalf of ISIS, an FBI agent testified at Santiago's bond hearing last week.
The agent did not elaborate on whether Santiago was purporting to be linked to ISIS or simply inspired by the terrorist organization.
Federal authorities in Alaska said Santiago told them before the attack that he was hearing voices and that his mind was being controlled by the CIA. He also made similar claims during an interrogation after the shooting.
But once he was transferred to the FBI office in Miramar, Florida, he introduced the ISIS claim and has not mentioned mind control, the agent testified.
The agent, who conducted the interview in Miramar, said only that Santiago claimed to be fighting for ISIS and that he'd been in touch via jihadi chat rooms with like-minded people who were also planning attacks.
ISIS has not claimed responsibility for the attack.
Santiago is charged in the federal indictment with 11 counts of performing an act of violence against a person at an airport serving international civil aviation that caused death or serious bodily injury, six counts of use and discharge of a firearm during and in relation to a crime of violence and five counts of causing the death of a person through the use of a firearm, according to a Department of Justice release.
Santiago is being held without bond. He is scheduled to be arraigned on Monday before United States Magistrate Judge Barry L. Seltzer in Fort Lauderdale.