Updated

A lawyer for an American couple sentenced to jail in Qatar over charges they starved their 8-year-old adopted daughter to death said Tuesday their defense team will keep pursuing efforts to allow the family to leave the Gulf nation while their case is appealed.

Matthew and Grace Huang were originally jailed in January 2013 and faced charges of murder following the death of their daughter, Gloria. They were released from prison in November, but were banned from leaving Qatar during their trial.

A court in the natural gas-rich OPEC nation sentenced the California couple to three years behind bars on March 27. They only learned that they had been convicted on a lesser child endangerment charge when the official judgment was received last week, according to a U.S.-based member of their legal team, Randy Papetti.

The Huangs say their adopted daughter, who was born in Ghana, died of medical problems complicated by unusual eating habits that included periods of binging and self-starvation. Defense witnesses have testified that the girl appeared healthy and active just days before her death.

Lawyers for the couple have vowed to appeal the case -- a process that got underway this week. Papetti told The Associated Press that members of the legal team have filed an intent to appeal the verdict but have yet to submit an appellate brief with supporting evidence.

They have repeatedly asked the court to let the Huangs leave the country to rejoin two other African-born adopted children, who left Qatar during the trial to live with relatives in the U.S. That request has been denied so far.

The prosecution, meanwhile, has raised the possibility of pursuing new charges of human trafficking during the appeal. Papetti said police and prosecutors have so far not offered any evidence to back up that allegation.

An investigative report by Qatari police had earlier raised questions about why the Huangs, who are of Asian descent, would adopt children who did not share their "hereditary traits."

"They're just having a hard time understanding that the Huangs would adopt children of a different race without strings attached," Papetti said.

The case has raised questions about possible cultural misunderstandings in Qatar.

The conservative Muslim country is seeking a higher international profile through major overseas investments and plans to host the 2022 soccer World Cup, but Western-style adoptions and cross-cultural families are relatively rare.

The U.S. State Department has expressed concerns about the case and said it has raised the issue with Qatari officials on multiple occasions. Qatar hosts an important American military air operations center at a desert air base outside the capital, Doha.

The next appellate hearing in the Huangs' case is scheduled for May 11.