After an investigation that spanned nearly five years and included hundreds of possible suspects, authorities in Tennessee said they believe a custody dispute was behind the killing of a National Guard member who was bound with zip ties and fatally shot in 2019.

Officials in Loudon County said Tuesday that Amanda Bishop, 39, and Eric Byrd, 39, were charged with first-degree murder in the killing of Jacob Bishop, a member of the Tennessee National Guard who had returned from a deployment to Poland in the months before he was fatally shot.

Amanda Bishop, of Kingston, and Byrd, of Lenoir City, were arrested Tuesday, the sheriff’s office said in a news release.

Their bonds were set at $1 million each, the sheriff’s office said in the release. Court records for the case weren’t available Thursday night, and it isn’t clear whether Byrd or Amanda Bishop, Jacob Bishop’s wife at the time of his killing, have lawyers to speak on their behalf.

Byrd is Amanda Bishop’s cousin, NBC affiliate WBIR of Knoxville reported.

During a news conference Tuesday, Loudon County Sheriff Jimmy Davis alleged that a custody dispute involving the couple’s child was heated and prompted the animosity that eventually led to Bishop’s killing.

Additional details about the dispute weren’t immediately available. Jacob Bishop’s relatives didn’t respond to requests for comment Thursday night. Contact information couldn’t be found for relatives of Amanda Bishop.

Authorities found Jacob Bishop dead at his apartment in Lenoir City, southwest of Knoxville, shortly before 8 a.m. on Oct. 1, 2019. He was bound and had been shot multiple times, the sheriff’s office said.

The sheriff’s office said his body was discovered by his mother, who told WBIR in 2021 that she’d gone to his home because he was late for work and believed he’d overslept.

“When you find your son dead on the floor in his apartment, that’s something that sticks in your brain,” Diane Bishop told the station. “It doesn’t go away.”

She said she didn’t want to make her son out to be a saint but said he was a “very good man,” she told the station.

In the 2021 report, former Loudon County Sheriff Tim Guidner told WBIR that the case was “complex” but that it had not gone cold and that it was being investigated daily.

The sheriff’s office said in a news release Tuesday that more than a dozen law enforcement agencies were involved in the investigation, including the FBI; the Secret Service; the Bureau of Alcohol, Tobacco, Firearms and Explosives; and a sheriff’s office in Texas.

In the 2021 report, WBIR noted that the sheriff’s office initially identified roughly 400 possible suspects with ties to Jacob Bishop. Asked about the figure at the news conference Tuesday and whether Amanda Bishop had previously been considered a top suspect, Davis said she was “always right up there at the top of the list.”

Davis attributed the arrests to good detective work and new technology. After five years of heartache and worry over whether the case would be solved, Davis said, it was a relief to finally tell Diane Bishop that two people were in custody in her son’s killing.

“I don’t think there’s really closure in a case like this,” he said. “But we can at least try and give her some justice.”

This article was originally published on NBCNews.com