FORT LAUDERDALE, Fla. — Looking frail and meek, Esteban Santiago, the man accused of fatally shooting five people at the Fort Lauderdale airport three days ago, appeared in federal court Monday to hear the charges against him and was orderd detained.

Shackled, bearded, and wearing a red jumpsuit, Santiago was assigned a public defender because he cannot afford a lawyer.

He answered questions briefly and in a clear voice, saying he understood the murder and other charges against him. Santiago, 26, may face the death penalty or life in prison if convicted.

Magistrate Judge Alicia O. Valle set a detention hearing for Jan. 17, followed by an arraignment for entering a plea on Jan. 23.

Santiago, an Iraq War veteran who grew up in Puerto Rico, took several deep breaths and jiggled his legs nervously as he waited for the judge. Federal marshals towered over him when he stood.

The charges include committing violence against people at an international airport resulting in death, and two firearms offenses.

Valle told Santiago the death penalty could apply. ‘‘We are telling you the maximum penalty allowed by law so that you understand the seriousness of the charges,’’ the judge said.

Speaking with a slight Spanish accent, Santiago told Valle he had $5 or $10 in his checking account, owned no property, and had not held a job since November. He said he had been in the Army, where he made about $15,000 a year.

That was the same month he walked into an FBI office in Alaska carrying an ammunition clip — leaving a pistol and his infant son in his car — to complain about a CIA plot against him. FBI agents called the local police, who took him to a psychiatric center where he spent a few days.

Before November, Santiago had spent nearly three years working security for Signal 88 in Anchorage, Ala., where he earned $2,100 a month, he said. He also spent about 10 years in the Army, where he earned $15,000 a year in his last three years of service.

More than a dozen officers kept watch outside the courthouse Monday, carrying rifles and wearing bulletproof vests. There were also mounted police and police dogs.

Law enforcement agents said they do not know why Santiago opened fire Friday in the baggage claim area of Terminal 2 at Fort Lauderdale-Hollywood International Airport or why he chose that airport.

He had boarded a flight from Alaska to Fort Lauderdale, having checked his handgun. After arriving, he picked up baggage containing the handgun, loaded the weapon in a restroom, and then began randomly shooting as passengers waited for their luggage.

When he ran out of ammunition, Santiago lay on the ground and surrendered to police, law enforcement officials said. It was all over within 70 seconds.

But the chaos lasted many hours. Rumors of a second gunman led to a shutdown of the airport and a mad scramble by passengers and airport workers.