SAVANNAH — Army Pvt. Isaac Aguigui held the Army’s lowest rank, served in the military less than two years and never saw combat. Yet Georgia prosecutors say the 21-year-old soldier from Cashmere, Wash., commanded enough authority to form an anti-government militia within the U.S. military with soldiers of greater rank and experience following his orders — including an order to commit murder.

That an untested soldier might possess such power adds another odd twist to an unfolding legal case full of stunning allegations.

Prosecutors in Long County said in court this week that Aguigui and three fellow soldiers on Fort Stewart killed a former Army comrade and his girlfriend last December. Their motive, prosecutors said, was to protect a secret plot to assassinate the president and overthrow the U.S. government — and along the way to bomb a park fountain in nearby Savannah, poison apple orchards in Washington state and take over the Army post where they were stationed. Authorities say the group stockpiled guns and bomb components that were seized from their homes and a storage locker.

Federal authorities have not said publicly whether they considered Aguigui and his associates a serious threat. One private group that monitors home-grown terrorism said it had never heard of Aguigui or his militia group.

“They were never on our radar screen,” said Mark Potok, an expert on militia and hate groups for the Southern Poverty Law Center in Montgomery, Ala. “You’d think the whole thing would be a joke except for that two people died and that they apparently spent $87,000 on guns.”

Among the other details that emerged this week: Authorities say Aguigui funded the weapons purchases using a $500,000 in life insurance benefits from the 2011 death of his pregnant wife — a death that authorities call “highly suspicious.” And in a videotaped interview with military investigators, a prosecutor said, Aguigui called himself “the nicest cold-blooded murderer you will ever meet.”

Aguigui was back in court Thursday along with two fellow soldiers for arraignment on charges including malice murder, felony murder and illegal gang activity in the Dec. 4 slayings of former Army Pvt. Michael Roark and his 17-year-old girlfriend, Tiffany York. Defense attorneys for the three men did not return messages from The Associated Press.

The three are being prosecuted in Georgia’s Atlantic Judicial Circuit. The Army filed murder charges against them in March, but dropped them Aug. 15.

A fourth Fort Stewart soldier pleaded guilty to reduced charges Tuesday and told a judge Aguigui ordered two older, more experienced soldiers to commit the killings.

Pfc. Michael Burnett, the soldier who cut the plea deal, told the judge that Sgt. Anthony Peden, a 26-year-old veteran of two tours in Afghanistan whose Army record lists 16 medals and commendations, shot the teenage girl twice at Aguigui’s command. Burnett also testified Pvt. Christopher Salmon, 26, with one Iraq tour on his service record, put Roark on his knees and shot him in the head.

Prosecutor Isabel Pauley said Aguigui targeted troubled soldiers for his militia, which he called F.E.A.R. — Forever Enduring Always Ready. Whatever the young private lacked in rank and combat experience, he had something else: roughly $500,000. Pauley said he received the life insurance and benefit payments after his wife, Army Sgt. Deirdre Aguigui, died.

Prosecutors say Aguigui bought $87,000 worth of semi-automatic assault rifles, other guns and bomb-making materials. Aguigui would give Roark money to buy weapons for him, the slain soldier’s father said.

“They were using Michael and other kids as straw buyers, giving them money to go buy guns,” said Brett Roark, citing conversations with prosecutors. “He wasn’t a member of the gang.”

Roark and his girlfriend were killed two days after Roark left the Army. The slain girl’s older brother said he knew something was wrong when Roark started giving her cash and expensive clothes, sunglasses and other gifts.

“An E-1 (private) in the military does not make big money like he was giving Tiffany,” said Nicholas Lee York, who said his sister told him that she and Roark had a “rich friend.” “I heard about their friend Isaac Aguigui and how he would give them a bunch of money.”

Aguigui grew up with six siblings in a military family in the state of Washington. Their father, according to a short alumnus profile on his high school’s website, retired after serving 20 years in the Army. Articles from Aguigui’s hometown newspaper, The Wenatchee World, say Aguigui was home-schooled. His father, Edward Aguigui, did not return a phone message seeking comment.

Isaac Aguigui joined the Army and enrolled in the U.S. Military Academy Prep School, which prepares cadets for admission to West Point, but he never became an officer. Instead, Aguigui’s service record shows he arrived at Fort Stewart in November 2010 as a private, working as an intelligence analyst in the Army’s 3rd Infantry Division.

Aguigui came to Fort Stewart to join his wife, an Army linguist whom he’d met at the military prep school, according to her obituary. After she returned home from a deployment to Iraq, Deirdre Aguigui became pregnant. A few months later, on July 17, 2011, she was found dead at the couple’s home on the Army post. Their unborn son was also lost.

Prosecutor Pauley said in court Tuesday the death of Aguigui’s wife was “highly suspicious,” but civilian prosecutors and military investigators declined to elaborate. Her father, Alma Wetzker, also declined to discuss his daughter’s death, saying it was still being investigated.

Regina Ross-Schmid, an Army spouse on Fort Stewart and friend of Aguigui’s wife, said soldiers who served with the woman were never given an explanation of her death.

“When we first were told she had died, what was said was she laid down to take a nap and when Isaac went to wake her up, he couldn’t wake her up,” Ross-Schmid said.

Ross-Schmid said she met the Aguigui for the first time at a memorial service for his wife on Fort Stewart.

“Everybody who spoke at the memorial was trying to choke back tears, these big strong Army men, and he’s not showing any emotion at all,” she said. “At the time I said, maybe he’s in shock. I don’t know. I can’t explain it. It just seemed odd.”