Private Isaac Aguigui of Cashmere, Washington, is lead into a Long County, Georgia, courtroom. A military judge has sentenced Aguigui to life in prison with no chance of parole for the 2011 slaying of his pregnant wife. File picture: Lewis Levine

Fort Stewart, Georgia -

An Army soldier accused of strangling his pregnant wife so he could pocket $500 000 in benefit money was convicted on Thursday by a military judge in a case that hinged on duelling medical experts who couldn't agree on how the woman died.

Private Isaac Aguigui, 22, was sentenced to life in prison with no chance of parole at the end of his four day court-martial at Fort Stewart. A military judge found him guilty of murder and causing the death of an unborn child. His wife, 24-year-old Sergeant Deirdre Aguigui, was about seven months pregnant when she was found dead in their apartment on July 17, 2011.

The verdict should have little impact on Isaac Aguigui's overall fate. He's already serving life without parole at a Georgia prison after pleading guilty last summer to murder charges in a double slaying that occurred nearly five months after his wife died.

Isaac and Deirdre Aguigui met at a military prep school in 2009 and were married months later. But friends testified that by the summer of 2011, their marriage had been strained by his drug use and infidelities by both spouses. Friends said Isaac Aguigui doubted the child his wife carried was his and he wanted a divorce.

Prosecutors had no problem presenting a motive. Weeks after his wife died, Aguigui received $500 000 in life insurance money and military death benefits. Evidence showed that hours before his wife died, Aguigui sent a text message to a former girlfriend: “We'll have plenty of money. All need is your body whenever I want it.”

But evidence of what specifically killed Deirdre Aguigui proved scant. The military's autopsy found more than 20 bruises and scrapes on the body including on her head and back, none fatal. Wounds on both wrists appeared to match a pair of handcuffs found on the couple's bed. But an official cause of death was not determined. The military couldn't decide whether she had been slain or died from natural causes.

Last year, a Georgia state medical examiner offered a second opinion. By ruling out illnesses, drugs or poisons, allergic reactions and other potential causes - and by noting the wrist wounds and other injuries - Dr James Downs concluded Deirdre Aguigui was strangled while struggling violently against handcuffs behind her back. He said a certain chokehold taught to soldiers could kill while leaving few if any telltale marks.

A former Army buddy, Michael Schaefer, testified that a month after his wife's death, Aguigui gloated that he had handcuffed her during sex and strangled her with a plastic bag over her head. Defence attorneys noted that Schaefer, who had spoken to Army investigators and testified previously at a pre-trial hearing, had never before mentioned a confession.

Aguigui told investigators his wife liked to have her hands bound during sex and that she wore the handcuffs consensually.

Last July, Aguigui pleaded guilty in the December 2011 slayings of former soldier Michael Roark and his girlfriend, Tiffany York, who were shot in the head near Fort Stewart. Civilian prosecutors say Aguigui used money from his wife's insurance policy to fund an anti-government militia group of disgruntled soldiers and ordered the couple killed to protect the group. Records show he bought at least $30 000 worth of guns and ammunition.

Now sentenced for murder both in civilian court and by the Army, it's unclear where Aguigui will end up serving his time. For now, he's expected to remain imprisoned in Georgia. - Sapa-AP