A look at the six inmates on U.S. military death row at Fort Leavenworth, Kansas, according to the Death Penalty Information Center. A federal judge in Kansas lifted a stay of execution for one of the inmates. The U.S. military carried out its last execution when it hanged Army Pvt. John Bennett in 1961 for raping and trying to kill an 11-year-old Austrian girl. The death chamber has since been remodeled for lethal injections.

RONALD A. GRAY

Gray was convicted and ordered condemned in military court in 1988 for two murders and three rapes in the Fayetteville, North Carolina, area while he was stationed at Fort Bragg, where he reached the rank of specialist and was a cook. He pleaded guilty in civilian courts to two other killings and five rapes and was sentenced to eight life terms, including three to be served one after the other. A federal judge in Kansas last week lifted a stay of execution for Gray.

DWIGHT LOVING

Loving, formerly of Rochester, New York, was convicted of killing Killeen, Texas, taxi drivers Bobby Sharbino and Christopher Fay during separate robberies on Dec. 11, 1988, while Loving was stationed at Fort Hood. In 1996, the U.S. Supreme Court, in an appeal by Loving, a former Army private, upheld the military death penalty, ruling that President Ronald Reagan in 1994 properly enacted a key section aimed at helping jurors decide who deserves capital punishment.

HASAN AKBAR

Akbar was condemned after being convicted of killing two fellow soldiers — Army Capt. Christopher S. Seifert and Air Force Maj. Gregory L. Stone — and injuring 14 others in an attack in Kuwait in 2003, during the early days of the Iraq war. In October, the U.S. Supreme Court rejected Akbar's appeal, which focused on whether the way in which the armed forces imposes a death sentence complies with recent Supreme Court rulings.

NIDAL HASAN

Hasan, an Army psychiatrist, was convicted of killing 13 people and injuring 31 others in the 2009 attack at Fort Hood in Texas, where Hasan opened fire in a room of unarmed soldiers. During his 2013 trial, Hasan told jurors he had "switched sides" in what he called America's war with Islam. He admitted beginning the rampage by pulling out a pistol and shouting "Allahu akbar" (God is great) and said he wanted to stop American soldiers from being deployed to kill fellow Muslims. A Fort Hood police officer helped end the attack in a gunfight with Hasan.

ANDREW WITT

Witt was convicted in 2005 of fatally stabbing a fellow airman and his wife at their duplex at Robins Air Force Base in Georgia, as well as wounding a staff sergeant. Prosecutors said Witt killed Senior Airman Andrew Schliepsiek and his wife, Jamie, after they threatened to report he had made a pass at Jamie Schliepsiek and had an affair with an officer's wife. Witt's lawyers did not dispute that he stabbed the couple but contended that the killings were not planned. Officials said the killings were the first ever at the 60-year-old Air Force base in central Georgia.

TIMOTHY HENNIS

Hennis, a former Army master sergeant at North Carolina's Fort Bragg, was convicted during an April 2010 court-martial trial of killing a North Carolina mother and two of her daughters, ages 5 and 3, in 1985. Hennis was first convicted in state court of the killings, but that conviction was overturned on appeal and he was acquitted in a retrial in 1989. Hennis was living in Lakewood, Washington, when the Army brought him out of retirement for the court-martial nearly two decades after his acquittal. A four-judge Army appellate panel last month upheld Hennis' death sentence.