Image caption Carri Williams was convicted of the most serious charges

A US couple has been convicted of the manslaughter of a teenage girl they adopted from Ethiopia.

Larry and Carri Williams, of Washington state, starved and beat Hana Williams until she died in the backyard of their home in May 2011.

They were also convicted of the first-degree assault of a younger boy they had adopted from Ethiopia.

Defence lawyers conceded that the couple were bad parents, but argued that they were not criminals.

Hana's paperwork when she was adopted in 2008 indicated she would have been about 13 years old at the time of her death.

The husband and wife blamed each other throughout the trial, according to the Skagit Valley Herald.

She was found guilty of homicide by abuse and first-degree manslaughter.

He was convicted of manslaughter; the jury could not reach a verdict on homicide.

The couple, from the city of Sedro-Woolley, are expected to face a maximum life sentence.