American Eric Volz went into hiding Friday after hastily leaving Nicaragua, where an appeals court overturned his conviction and 30-year-sentence in the slaying of his Nicaraguan girlfriend.

The judge's decision to free Volz sparked outrage among some Nicaraguans who say the American received favorable treatment in the local justice system and should not have been freed.

Volz went into hiding after leaving Nicaragua because of "reports of threats" against him, Volz family spokeswoman Melissa Campbell said in an e-mail to The Associated Press.

His mother, Maggie Anthony, arrived back in the United States from Nicaragua on Friday evening and said Volz was not yet in the country.

"I'll worry about him until he's on U.S. soil," she said.

Anthony said she could not disclose where he was nor how soon he would return.

The 28-year-old from Nashville, Tenn., accompanied by Anthony, was freed Friday from a Nicaraguan prison hospital where he was being treated for kidney stones. He was then driven by police-escorted ambulance to sign his release papers, then rushed to the airport.

"Eric Volz was released from a Nicaraguan prison hospital earlier today and will be in hiding, due to reports of threats against him," Campbell's statement read. "We have reason to believe he is being followed and are taking every precaution to assure his safety."

Volz left Nicaragua at 2:45 p.m. local time (3:45 EST), State Department spokesman Kurtis Cooper said in Washington.

"We are pleased that the Nicaraguan Appeals Court decision ... has been implemented in accordance with Nicaraguan law," he said.

An appeals court on Monday overturned Volz's conviction in the November 2006 death of 25-year-old Doris Ivania Jimenez, enraging prosecutors, human rights and women's rights activists who believe Volz is guilty.

Prosecutors said the victim put up a fight, matching scratch marks on Volz's shoulder. They also said he told an assistant to rent a car for him because "someone has died" before he said he learned of her death. The victim's mother said he had threatened to kill her daughter before.

Volz and a Nicaraguan man, Julio Martin Chamorro, were sentenced in February for the death of Jimenez, who was found raped and strangled in a clothing store she owned in Rivas, 55 miles south of Managua. The court upheld Chamorro's conviction in the murder.

A surfer-turned-real-estate-broker who also founded a local magazine in Nicaragua, Volz has claimed his innocence all along, saying he was two hours away from the crime scene at the time.

The appeals court cited "reasonable doubt" in overturning Volz's conviction. The defense had argued that records show Volz's personal cell phone was answered in Managua, the capital, around the time of the killing.

Nicaraguans were both outraged at the brutal death of the young, attractive Jimenez, and suspicious that, as an American, Volz might be able to use money or influence to avoid punishment.

Increasing numbers of American have moved to Nicaragua — the second-poorest country in the hemisphere after Haiti — in recent years, buying up beachfront property and building second homes.

Volz's release was ordered by the same judge who convicted him, a step that is required by Nicaraguan law.

Judge Ivett Toruno, who convicted Volz, waited four days before agreeing to release him, citing problems with the files.

Volz's attorney claimed the judge was delaying the process to allow time for another appeal. It wasn't clear Friday where that effort stood.