MIAMI -

Jill Tahmooressi is back in South Florida after a Mexican judge refused to dismiss the weapons charges against her son.

"Oh, very sad. I know Andrew is extremely despondent, so my concern is for him because he's been through a lot," she said.

U.S. Marine reservist Andrew Tahmooressi was ordered back in a jail near Tijuana, where he has been locked up for more than three months.

On Wednesday, he arrived at a courthouse under heavy guard and would spend more than eight hours inside pleading his case. The 26-year-old maintains that the night of March 31, he got lost and crossed the Mexican border by accident with three firearms in his pickup truck.

"The judge, the honorable judge did let me go in and visit him the last 20 minutes, so I was able to see him and that's why I know how despondent he is," Jill Tahmooressi said. "Because, that point, after the nine hours he knew he wasn't coming home."

The legal system in Mexico is sometimes unpredictable, and unlike in the United States, a person is guilty until proven innocent.

Nonetheless, Jill Tahmooressi said she and her attorney, Fernando Benitez, are hopeful the case will be dismissed.

"He's jailed. I'm free. So I have to be his advocate," she said.

Andrew Tahmooressi's next hearing is scheduled Aug. 4.