Reported by Samantha Riley:

For 30 years the trail had been cold - Major Chester Garrett, a decorated U.S. Army officer, found murdered in the desert near El Paso, Texas in January 1977. Now, police say they have arrested his stepson and estranged wife.

Maj. Garrett was 36 when he was found dead. He had suffered blunt force trauma to the head, and stab wounds as well. At the time, local authorities pursued leads, but eventually the case went cold.

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It was only in 2006 that the case was reopened after family members contacted the El Paso County Sheriff's Office to review the case. "New information and new leads developed and the case was reopened," said El Paso Public Information Officer Angelica Becerra in an email to ABC News. She would not be more specific about the new information. "[The] family was looking for justice."

The trail led investigators across state lines to Knoxville, Tennessee. Investigators say Maj. Garrett's stepson, Roger Garrett, 54, had been living there for 2-3 months and had recently been fired from his job. Police went to his apartment, found it empty, and called his cellphone.

Roger Garrett and Lizbeth Ann Garrett, suspected in the 1977 killing of Maj. Chester Garrett. Knox County Sheriff''s Office|El Paso County Sheriff

"Obviously he didn't know we were calling about the homicide," Knoxville Public Information Officer Darrell DeBusk told ABC's Knoxville affiliate, WATE. "He thought we were calling about another issue and he made the suggestion for him to come by. When he did we placed him into custody."

Meanwhile in El Paso, police arrested Lizbeth Ann Garrett, 74. She had been Maj. Garrett's wife.

"According to military authorities he was one of the most highly decorated soldiers in the Vietnam era." Sgt. Jim Belknat of the El Paso County Sheriff's Office told WATE. The El Paso Times also reports that at the time of his death he was the executive officer of the student battalion at the Air Defense School at Fort Bliss, where he was stationed.

Investigators have not cited a possible motive for the killing. Both Roger Garrett and Lizbeth Ann Garrett are charged with murder and are each being held on $5 million bond.

"From what we've learned, the man was real tough - a Special Forces type, almost what you'd call a superman," Sheriff's Capt. Mac Stout was quoted as telling the El Paso Herald-Post in 1977. "Whoever got him must have been mighty tough, too, and probably more than one, and probably took him by surprise."