(CNN) A pilot for a subsidiary of American Airlines was arrested at Louisville International Airport after he was indicted in connection with the 2015 deaths of a Kentucky couple and their neighbor, authorities said.

Christian Richard Martin, 51, is accused of killing Calvin and Pamela Phillips and Edward Dansereau in November 2015, Kentucky Attorney General Andy Beshear said.

Calvin Phillips was found shot to death in his Pembroke home on or about November 18, 2015, Beshear said in a statement. The bodies of Pamela Phillips and Dansereau were found a few miles away in a cornfield in her burned car.

A Christian County grand jury indicted Martin on Friday on three counts of murder (a capital felony); one count of arson; one count of attempted arson; two counts of burglary in the first degree and three counts of tampering with physical evidence, according to the grand jury document. The indictment was sealed until he was taken into custody Saturday, Beshear said.

The attorney general, speaking to reporters Monday, said he believes he has a "very compelling case."

"I hope (the arrest) brings a little bit of justice and a little bit of relief to those families," he said.

Martin was arrested at the airport to ensure the safety of law enforcement officers and the public, Beshear said. He now lives near Raleigh, North Carolina, the attorney general added.

Martin will be formally charged in court on May 22, Beshear said.

Martin's family is devastated, said Tucker Richardson, Martin's former lawyer. He vouched for Martin's character, saying he joined the military in response to the September 11 attacks.

Martin would have turned himself in if he had known authorities intended to arrest him, Richardson said.

The victims' families welcomed the news, in a joint statement through the attorney general's office.

"Every day, we are haunted by what was done to them and haunted further that someone was still free to do as they wish, beyond the civility of mankind or laws of our nation," the families said.

"We look forward to justice in court, and we look forward to a verdict to bring an end to this terror, and a fresh start at healing."

Beshear said he accepted a request from the local commonwealth's attorney two years ago to appoint a special prosecutor to the case after the family's son had expressed concern that investigations had stalled.

Victim may have been expected to testify against his accused killer

John Kelly, a representative for the Phillips family, said Calvin Phillips was due to testify against Martin in a court case in 2015 when he and his wife were killed.

Richardson countered that notion by claiming he hired an investigator to interview Calvin Phillips.

The private investigator determined Calvin Phillips would be a star witness for Martin's side, Richardson said.

"If there is a poster child for 'life is not fair,' it would be a picture of Kit Martin," Richardson said. "They took a fine man and drug him through the mud."

Martin was kicked out of the military after lengthy career

Martin, who over a period of 30 years served in the Army Reserve, Army National Guard and on active duty, was punitively dismissed from the service in August 2016 following a court-martial.

He was found guilty of two counts of mishandling classified information and of assault on a child under the age of 16, military records show.

Martin was sentenced to be reprimanded, forfeit all pay, be confined for 90 days and to be dismissed from the service.

The Leaf-Chronicle of Clarksville, Tennessee, reported Philips had been scheduled to testify in the court-martial when it was originally supposed to have been held in December 2015. The report said the Phillips lived across the street from the Martins.

'Like something in a movie'

At the Louisville airport where Martin was arrested, passengers expressed shock, according to CNN affiliate WDRB

Ashley Martin and her mother, Frances Wise, were waiting to board an American Airlines flight from Louisville to Charlotte when they heard their pilot had been arrested.

"It was like something you would totally see in a movie," Martin -- no relation to the accused -- said.

"It was very tense," her mother told WDRB . "You could tell the employees knew something was going on."

The women assumed their pilot had been intoxicated and learned of the reason for his arrest later in the day.

"It's startling," said Martin. "It's scary to think this happened so long ago, and they're just now getting around to catching the guy."

Pilot flies for regional airline

American Airlines says Martin was a pilot for regional subsidiary PSA Airlines.

"All of us at American Airlines and PSA Airlines are deeply saddened to have learned about these allegations from 2015. Our team was made aware of the indictment this morning after his arrest at Louisville International Airport," it said in a statement.

"We have an unwavering commitment to the safety and security of our customers and team members, and we will provide any investigative assistance possible to law enforcement throughout their investigation."

The airline said Martin has been placed on administrative suspension pending the outcome of the investigation and court proceedings, which includes the suspension of all travel privileges.