The Idaho Supreme Court ruled Wednesday that two orphaned children will remain with their grandmother in Argentina, not with family members in California who also wanted custody.

The ruling means that Alden and Aliana Heiss will stay with Violeta Conti in Ushuaia, a region dubbed "the end of the world" by locals.

The children's parents, Karl Heiss and Marisa Bauducco-Heiss, of Bonners Ferry, Idaho, were killed in a car crash near Seattle last year. Aliana, who was 10 at the time of the crash, sustained severe brain damage in the crash; Alden, who was 6, suffered whiplash but has fully recovered.

The parents had handwritten wills granting custody to Conti, but paternal grandparents Fred and Anna Belle Heiss, of Malibu, Calif., sought custody. They contended Aliana needed medical care only available in the U.S. and that Alden would heal better from the emotional trauma if he was in a familiar setting.

"Oh, this is terrible," Anna Belle Heiss said after learning of the ruling. "So my grandchildren are gone for good, my children are gone for good _ you have no idea how terrible this is."

Conti said after the ruling that it was "tremendous news."

"We had no idea it would come so quickly," she added.

In the 14-page unanimous ruling, Chief Justice Daniel Eismann said state law, which places the deceased parents' wishes first when determining guardianship, doesn't jibe with the Heisses' contention that the best interests of the children should be the primary factor in determining custody.

"It is the legislature that has the power to change the statutes, not this Court," Eismann wrote. "The legislature obviously believed that parents should be able to direct who will have guardianship of their unmarried minor children in the event of the parents' deaths."

Eismann said the father, Karl Heiss, was "empowered" to choose his wife's mother as the children's guardian under state law.

Besides upholding the parents' choice of Conti as guardian, the high court also overturned a lower court ruling that made the Heisses co-guardians while the children visit for one month of the year.

That arrangement could cause more problems than it solved, Eismann wrote.

The custody battle flared shortly after the Oct. 2008 car crash, while Aliana was still on life support at a Seattle hospital and doctors were unsure if she would survive. With no translator available, Conti and her family were left trying to understand doctors' opinions.