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A frustrated judge, begrudging prosecutors and chagrinned family members all conceded Thursday that offering a plea deal to a southeast Missouri man accused of killing his estranged wife, a mother of 5-year-old triplets who was missing for almost two years before her body was found last week on an island in the nearby Mississippi River, was inadequate.

But it was the best option available, they said, because 42-year-old James Clay Waller II was the only person who could lead authorities to Jacque Waller's body, while ensuring a conviction and offering grieving family members closure for the39-year-old mother who disappeared in 2011.

Clay Waller was given a 20-year prison sentence Thursday after pleading guilty to second-degree murder and admitting in a barely audible voice -- inside a packed Cape Girardeau County courthouse -- that he'd murdered the triplet's mom. The shaken inmate struggled to admit choking his wife to death before dumping her body on a nearby island in the Mississippi River nearly two years ago.

Before being sentenced, Clay Walker also listened to his 7-year-old son publicly disown him for life.

But few left the courthouse satisfied with the outcome. Both Jacque Waller's sister and Circuit Judge Benjamin Lewis said they weren't happy with the lighter sentence, but had few options. The plea was conditional on Clay Waller II leading investigators to his wife's body and his confession in court. Her body wasn't found until May 29 in Alexander County, Ill.

"I did not want this deal," said Waller's sister, Cheryl Brenneke, who has custody of the triplets and plans to adopt the two girls and one boy. "My mother and father and these children deserved to bury her, though."

Lewis acknowledged that "there will be a number of people critical of this plea agreement. However none of those critics could provide the body of Jacque Waller."

"That is not what you deserve, but it will have to do," he said in handing down the 20-year sentence. Under the original charge, Waller could have faced the death penalty or life in prison without parole. The plea was conditional on him leading investigators to his wife's body and his confession in cour

Clay Waller is serving a five-year term in federal prison for threatening Brenneke over the Internet. His sentence in the murder case will run concurrent with the federal case, officials said.

He was originally charged with first-degree murder and arrested in April 2012 even though her body had not yet been found. He had faced a September trial in Cape Girardeau County Circuit Court.

Jacque Waller went missing on June 1, 2011, the same day the couple met with a divorce lawyer and argued over money after living apart for the previous three months.

Her Honda Pilot was found along Interstate 55 a day after she disappeared, its tires slashed, after the car had been seen the day before at Clay Waller's home. Several searches since then turned up sporadic leads, including the discovery of her purse near where the car was found.

The FBI said last year that Clay Waller suggested to his father that he had broken Jacque Waller's neck and buried her in a hole that he had dug in advance. But Clay Waller had previously not made any confession to police, and his father died before he could testify.

Waller spoke softly as he admitted guilt, his voice barely audible in the packed Jackson courtroom. He kept his back turned as Brenneke spoke, facing the judge but glancing downward while fidgeting in place.

"We got in an argument," he said, describing an assault on his wife at the Jackson home he was living in after the couple split. "I lost my temper."

After Brenneke spoke, Waller heard a taped statement by his son in which the child said, "I never want to see you again for my entire life."

Before her death, Jacque Waller had again found love with a new boyfriend, her sister said Thursday.  Brenekke spoke to Waller with rage and contempt, her voice quavering.

"To someone who has always considered himself the smartest guy in the room, you just look like a skinny, washed up, murdering con man to everyone in this room," she said. "I knew immediately that you killed my sister."