In 2006, the Army forced Hennis, who was retired, back into active duty to face new charges in the triple slaying of Kathryn Eastburn and her two daughters - 5-year-old Kara Sue and 3-year-old Erin Nicole.
During his trial, prosecutors said DNA found in sperm left in Eastburn's body matched Hennis.
This was Hennis's third trial for the killings. A civilian jury acquitted him in 1989 after the NC Supreme Court overturned his initial conviction in 1986. Hennis couldn't be tried again in civilian court, so he was charged by the military, which can pursue the case because its court system is a different jurisdiction.
Hennis, who had adopted the Eastburns' dog several days before the killings, was arrested four days after the bodies were found when a witness who saw him in the Eastburn's driveway picked him out of a photo lineup.
Eastburn's husband, Air Force Capt. Gary Eastburn, was in Alabama at squadron officer's training school at the time of the stabbings. The Eastburns' 22-month-old daughter, Jana, was at the home but was left unharmed in her crib.
The case spawned a 1993 book entitled "Innocent Victims," which was followed by a cable television miniseries.
Throughout his military trial, Hennis's lawyers tried to discredit both the DNA evidence and eyewitness accounts. Defender Frank Spinner told the panel hearing the case that the DNA could have been left days earlier if Hennis and Eastburn were having an affair - a suggestion that visibly offended her family members watching in the courtroom.
"Does the evidence take you beyond adultery to murder?" Spinner asked the 14-member panel deciding Hennis' fate. "You should follow that evidence where ever it leads you, no matter how uncomfortable it may make you."
Prosecutor Capt. Matthew Scott dismissed that suggestion as "fantasy."
"The person that slaughtered her, raped her -- the person that raped her left his sperm," Scott said.
The military panel reached its verdict at 10:54 a.m. - finding Hennis guilty by unanimous vote.
Eastburn's husband and surviving child hugged each other and wept after the verdict was announced. Hennis, 52, reached back and squeezed wife Angela's hand before the decision was announced but he showed no reaction to the verdict. His wife cried.
The panel will decide Friday if Hennis should be put to death.
The defense asked the judge Thursday to limit family testimony during the sentencing phase - saying they were concerned that family members might lash out at Hennis. The judge said lawyers were free to object during testimony and he would rule then.
Despite the conviction, Hennis may have other legal avenues open to him. He's filed a lawsuit in federal court challenging the Army's right to try him. Lawyers claimed that once a soldier is discharged, he cannot be brought to court-martial for any crimes that happened before he was released from the service. They cited a 1986 Supreme Court case in their petition.
Hennis retired from the military in 2004 and was living in Lakewood, Washington before his latest arrest.