An airline pilot was arrested Saturday at Louisville Muhammad Ali International Airport after he was charged in the 2015 murders of three people.

A Christian County, Kentucky, grand jury charged Christian Richard Martin with three counts of murder, one of arson, one of attempted arson, burglary in the first degree and three counts of tampering with physical evidence. The indictment was unsealed Saturday after Martin's arrest.

Kentucky Attorney General Andy Beshear said Saturday that Martin was responsible for the 2015 murders of Calvin and Pamela Phillips and their neighbor Edward Dansereau.

Calvin Phillips was found fatally shot at home in Pembroke, Kentucky, Beshear said in a video Saturday. The bodies of Pamela Phillips and Dansereau were found in Calvin Phillips' vehicle, which had been set on fire in a corn field a few miles away from the couple's residence, he said.

​Crystal Staley, spokeswoman for the Kentucky Attorney General's office, said prosecutors could not yet discuss a possible motive.

The office took over the case in 2017 after the Phillips' son, Matt Phillips, came to Beshear and expressed fear that the investigation had gone cold.

Christian Richard Martin Christian County Detention Center

Prosecutors zeroed in on Martin, who had moved from the jurisdiction of the case, Christian County, Kentucky, to North Carolina, Beshear said.

"Today is an indictment and there will be many steps from here," the attorney general said. "But we hope this is one of example of when you never stop seeking justice, when you never give up on a case, that we can truly get important results for our families."

Relatives of the victims said in a statement Saturday that they have been "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."

"We look forward to a verdict to bring an end to this terror, and a fresh start at healing," they said.

Martin worked for PSA Airlines, a subsidiary of American Airlines, for slightly more than a year, American said in a statement. He was arrested as he prepared to fly as first officer on Flight 5523 from Louisville to Charlotte, North Carolina, the airline said.

Martin was grounded and placed on "administrative suspension" pending the outcome of the case, American said.

"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.