(Corrects autopsy report findings in paragraph three and rephrases paragraph four.)
DOHA, March 27 (Reuters) - A Los Angeles couple were sentenced to three years in jail in Qatar on Thursday for causing the death of their adopted daughter, who was found to have died of starvation, in a case that has raised concern in Washington.
Americans Matthew and Grace Huang were arrested in January 2013 year after their 8-year-old adopted daughter, Gloria, died unexpectedly.
An autopsy found that she had died of "cachexia and dehydration", while the prosecutor charged the couple with "murder with intent by forced starvation". Cachexia is an irreversible loss of body mass.
The couple argued that Gloria had been suffering from malnutrition-related diseases since they adopted her from Ghana at the age of 4, and that the Qatari authorities had failed to acknowledge this.
"We have just been wrongfully convicted and we feel as if we are being kidnapped by the Qatar judicial system," Matthew said. "This verdict is wrong and appears to be nothing more than an effort to save face."
In Washington, State Department spokeswoman Marie Harf said the United States was "surprised and disappointed by the trial court's decision."
Harf told a regular news briefing that U.S. officials "have had some concerns throughout the trial by indications that not all of the evidence was weighed by the court and that some cultural misunderstandings may have led to an unfair trial."
"We have talked to the government (of Qatar) about this. We will continue to. And I do believe there is some sort of appeal process," Harf said.
The judge reading the verdict did not specify what offence the couple had been convicted of, but the prosecution had earlier downgraded an original charge of premeditated murder to one of "murder by negligence".
David House, an international crisis agency working with the family, said the defence lawyer was expected to get a full briefing on the verdict within days.
A website created to publicise the case ( http://freemattandgrace.com ) said Matthew, a Stanford-trained engineer, had moved to Qatar with his wife and their three young children in 2012 to help oversee a big infrastructure project related to the 2022 soccer World Cup.
Gloria died on Jan. 15, 2013 and Qatari police charged the couple the next day. The website said the other children had been put in an orphanage.
No detailed explanation of the charges has been published, but the website said Qatari officials had concluded "that the murder may have been done in order to harvest her organs or to conduct medical experiments on her."
The pair spent nearly a year in prison before being released on their own recognizance but were not allowed to leave Qatar, the website said.
The judge said they had also been fined 15,000 riyals ($4,100) and would be expelled after completing their sentences. ($1 = 3.6415 Qatar riyals) (Reporting by Eman Kamal and Amena Bakr in Doha, Rania El Gamal in Dubai and Will Dunham in Washington; Writing by Sami Aboudi; Editing by Kevin Liffey and Cynthia Osterman)