LOS ANGELES -- In search of his mother, 8-year-old Jonathan Martinez journeyed with his teenage cousin from El Salvador to the Arizona-Mexico border in late 2004.

U.S. Border Patrol agents caught Jonathan trying to cross the desert and detained him for several days before turning him over to his mother, whom he hadn't seen for four years.

Since then, he's learned English, joined a soccer team and generally embraced life as an American fifth-grader. Except Jonathan isn't here legally -- and on Monday a judge may order him deported back to El Salvador.

Though his mother has been living and working legally near Los Angeles, a wrinkle in immigration law doesn't let her apply to keep him here.

"I don't want to go back because I'll be alone," said Jonathan, now a busy 10 year old.

His case illustrates a growing problem with the federal program known as "temporary protective status" under which Jonathan's mother is staying in the United States: what to do with thousands of kids from Central America who come to the United States illegally to be reunited with their parents.

The program provides legal residency for several years to illegal immigrants from El Salvador, Honduras and Nicaragua, all countries that have suffered devastating natural disasters in recent years. The idea is that those illegal immigrants have little to return to and that they can best serve their homelands by working here and sending money home.

But only immigrants in the United States when a program starts -- for Salvadorans, after two major earthquakes in 2001 -- are eligible. That can put children who later come seeking their parents in a sort of immigration limbo.

Jonathan is in such a situation.

Because he lives with his mother, he's not eligible for a special immigration status for minors who've been abandoned or abused. An asylum claim would be difficult to establish because it's hard to argue that a child faces political, religious or other persecution.

"They come to be reunited with a parent and find out they can't stay," said Judy London from Public Counsel, a Los Angeles law office that represents immigrant minors.

The U.S. government doesn't count how many detained minors have a parent with the temporary residency status, or how many are eventually deported. Immigration lawyers and advocates say such cases have skyrocketed in recent years.

That's in part because what were created as temporary programs have become de facto permanent. Since El Salvador's program began in 2001, U.S. Citizenship and Immigration Services has repeatedly extended it for the original recipients, who were initially given 18 months of legal U.S. residency. Today there are about 230,000 Salvadorans with the status, and another 85,000 Hondurans and Nicaraguans.

Meantime, children who years ago were left with relatives have gotten older and more determined to find their parents. In other cases, the guardian relative dies, or the situation becomes abusive, and a child starts heading north out of desperation.

The temporary program is not equipped to handle such circumstances.

"It's only for an individual in the United States at the time it was designated," said Citizenship and Immigration Services spokeswoman Marie Sebrechts.

Just under 115,000 children were caught attempting to illegally enter the United States last year, according to the Border Patrol. The majority were from Mexico and immediately deported.

Of the up to 20,000 non-Mexican minors detained each year, Honduras and El Salvador have had the highest number of apprehensions every year since 2000, according to the Border Patrol. Nicaragua isn't far behind.

After being detained, children such as Jonathan generally are handed over to a parent or guardian with legal residence, and then ordered to appear in immigration court. Immigration judges have some discretion and can decide that the government will no longer pursue deportation of a child whose parents have special residency.

The total number of administrative closures -- which includes children and other cases -- have been dropping since 2002, when 7,800 cases were closed compared to 5,838 last year, according to U.S. Department of Justice data.

Jonathan's lawyer, Julianne Donnelly, is hoping for that kind of a break Monday.

Jonathan's mother, Rosalia Montoya, said her son often pleaded to be reunited during phone conversations, but she never imagined he would actually journey north.

When the aunt he stayed with was hospitalized for an operation, he said he felt alone and started taking buses north with his cousin. Over several weeks, they traveled through Guatemala and Mexico before arriving at the U.S. border.

When Montoya, 32, learned he had disappeared from the aunt's house, she feared he had been killed by gangs. Now she worries about what to do if Jonathan is deported.

The aunt who took care of him has since left El Salvador, Montoya said, his grandparents are too old to take him in, and his father disappeared years ago.

Montoya could move back, but she worries about earning enough to raise Jonathan and his 3-year-old half sister, who was born in the United States.

"I'm nervous and worried," she said. "I say to myself, 'My God, what's going to happen when we go before the judge?"'