Pvt. Isaac Aguigui walks into the courtroom during a preliminary hearing at Long County Superior Court in Ludowici, Ga., in this 2012 file photo. Aguigui, accused by prosecutors in 2011 of plotting attacks as leader of an anti-government militia group, was charged by the Army today with murder in the 2011 death of his pregnant wife, Army Sgt. Deirdre Aguigui, and with the death of their unborn son.

SAVANNAH, Ga. - A Georgia soldier accused of plotting attacks as leader of an anti-government militia group was charged with murder by the Army on Wednesday in the 2011 death of his pregnant wife.

Pvt. Isaac Aguigui of Cashmere, Wash., will face a military hearing to determine if a court-martial should try him in the death of his wife, Army Sgt. Deirdre Aguigui, said Fort Stewart officials in southeast Georgia. The Army also charged Aguigui with causing the death of an unborn child, a boy, when his wife died in July 2011. Military authorities spent nearly two years investigating, but have not released any details about the killing.

"Every victim deserves to have their case prosecuted. In this case it took some time," said Fort Stewart spokesman Kevin Larson.

Less than five months after his wife's death, Aguigui and three fellow Fort Stewart soldiers were charged by civilian authorities in the December 2011 shooting deaths of Michael Roark, a former member of their Army unit, and Roark's 17-year-old girlfriend, Tiffany York. Civilian prosecutors are seeking the death penalty for Aguigui, saying he ordered the deaths to keep the couple from exposing the militia group.

Civilian prosecutors said in court last August that Aguigui, 21, recruited and led a group of disgruntled Army soldiers who plotted attacks ranging from bombing a park fountain in Savannah to poisoning apple crops in Washington state. They said the group also wanted to assassinate an American president, though prosecutors never specified if the target was President Barack Obama.

None of the attacks were ever carried out.

Prosecutors said in court that Aguigui used a $500,000 life insurance payout from his wife's death to buy guns and bomb-making materials.

Roark's father, Brett Roark, said the slayings of his son and York could have been prevented had the Army charged Aguigui sooner in his wife's death.

"The original command structure didn't do their job," Roark said. "This should have stopped at her murder."

Aguigui's attorney, Newell Hamilton, declined to comment on any of the charges against the soldier.

An Army linguist, Deirdre Aguigui became pregnant after returning home to Fort Stewart from a deployment to Iraq. A few months later, on July 17, 2011, the 24-year-old woman was found dead at the couple's home on the Army post.

It's not clear how Deirdre Aguigui died. Fort Stewart officials and the woman's family have declined to discuss her death because of an ongoing investigation.

Deirdre Aguigui's father, Alma Wetzker, said Wednesday he was told the investigation took time because the first medical examiner couldn't determine a cause of death. He a second medical examiner had to be called to make an official determination. Wetzker wouldn't discuss what the cause of death was ruled to be.

"I'm just finally glad that there's an end to the endless investigation so we can finally start to move on," Wetzker said.

According to her obituary, Deirdre Aguigui met her husband at the U.S. Military Academy Prep School, which prepares cadets for admission to West Point, but he never became an officer. Instead, Isaac Aguigui's service record shows he followed his wife in November 2010 to Fort Stewart, where the young private served as an intelligence analyst in the Army's 3rd Infantry Division.

Civilian prosecutors in Long County, where Roark and his girlfriend were found shot on Dec. 4, 2011, said Aguigui targeted troubled soldiers for the militia group that he called F.E.A.R. - Forever Enduring Always Ready. Roark's father has said Aguigui would give his 19-year-old son money to buy weapons for the group, but that Roark wasn't a militia member.

Prosecutors said Aguigui used the insurance payments from his wife's death to buy $87,000 worth of semi-automatic assault rifles, other guns and bomb-making materials recovered by investigators.

In addition to malice murder and felony murder, Aguigui faces state charges of criminal gang activity, aggravated assault and using a firearm while committing a felony. Despite prosecutors and witnesses describing the group's plots in open court, Aguigui and his fellow soldiers have not been charged under Georgia's terrorism statute.

One of the four soldiers arrested in Roark's death, Pfc. Michael Burnett, pleaded guilty to reduced charges last year. He told a judge that he was with Aguigui and two other soldiers when they led Roark and York out to the woods and killed them. Burnett said Sgt. Anthony Peden, a veteran of two tours in Afghanistan, shot the teenage girl twice at Aguigui's command. He also testified that Pvt. Christopher Salmon, who had served one tour in Iraq, put Roark on his knees and shot him in the head.

Civilian prosecutors are also seeking the death penalty for Peden and Salmon in those killings.