A couple in the US state of Washington have been convicted of the death of their 13-year-old adopted daughter, who they starved and froze to death after reading a religious parenting handbook.

Carri Williams was found guilty of homicide by abuse and manslaughter, while her husband was convicted of first-degree manslaughter.

The couple, from Sedro-Woolley, a town between Seattle and Vancouver, were arrested in September 2011 four months after their Ethiopian-born daughter Hana died in their back garden from hypothermia.

She had been found unconscious shortly after midnight in May 2011, in temperatures of around 4C.

An investigation into her death found she had suffered beatings and starvation, had been forced to sleep outside and use an outdoor toilet.

She had lost a significant amount of weight in the three years she lived at the Williams', and her 10-year-old brother suffered similar treatment. The couple was also found guilty of assaulting him.

Carri and Larry Williams had kept the children isolated by home schooling them, and used the controversial Christian parenting book To Train Up a Child to raise them.

The book, by husband and wife Michael and Debi Pearl, advocates the use of physical violence towards children before the need for discipline arises.

"As you come to understand the difference between training and discipline, you will have a renewed vision for your family, no more raised voices, no contention, no bad attitudes, fewer spankings, a cheerful atmosphere in the home, and total obedience from your children," the Pearls say.

To Train Up a Child
To Train Up a Child advocates physical violence towards children (No Greater Joy)

In the book, the couple advises "switching" a seven-month old baby for crying and clenching his fists for not getting his own way.

They suggest using tools instead of hands for hitting children, suggesting willow-branch for babies and a quarter-inch plumbing supply line for older children, which Michael Pearl says is "too light to cause damage to the muscle or the bone".

According to kirotv.com, one witness in the Williams trial told how the book instructed parents to give unruly children cold baths, withhold food and force children outside in cold weather as punishment.

To Train Up a Child has previously been linked to the death of two other children in the US.

Seven-year-old Liberian-born Lydia Schatz was also killed by her adoptive parents in 2010 after they used To Train Up a Child.

She was hit with a plastic tube for hours at their home in California for allegedly mispronouncing a word and died in hospital a day later from her injuries. Parents Kevin and Elizabeth Schatz were both found guilty of causing her death.

Sean Paddock, a four-year-old from North Carolina, was killed by his mother Lynn after she bought To Train Up a Child. He was beaten with plastic tubing to discipline him but when this did not work, she bound him so tightly in blankets that he suffocated.

The Pearls have always denied their book advocates abuse, with Michael Pearl addressing his critics after Lydia's death by saying: "I laugh at my caustic critics, for our properly spanked and trained children grow to maturity in great peace and love."

Responding to Hana's death, he added: "We share in the sadness over the tragic death of Hana Williams. What her parents allegedly did is diametrically opposed to the philosophy of No Greater Joy Ministries and what is taught in the book.

"We are grieved by Hanna's [sic] death as well as the nearly 1,700 other children that die in this country every year as the result of neglect or abuse."

He listed several passages of the book that he said warned against abuse.

"If, as alleged, Hanna's parents owned a copy of the book, it is obvious from these quotes and their actions, that they either have not read it or totally ignored its contents.

"The alleged presence of the book makes it no more responsible for Hanna's death than the presence of a weight loss book in the home of an overweight person is responsible for their obesity."

Debi and Michael Pearl
Michael Pearl defended his book, saying it directly warns against child abuse (Facebook)