TIJUANA, Mexico — Eight-year-old Saul Arellano joined his mother in Mexico on Thursday following her loss in a yearlong fight to stay in the United States despite her status as an undocumented migrant.

Elvira Arellano told a news conference in Tijuana that her son Saul, who was born in the U.S. and is an American citizen, will enter third grade in her native state of Michoacan.

But Arellano said she will continue to travel and work for immigration reform in Mexico City and the border city of Tijuana on behalf of her Latin Family United organization.

"I am not going to stay away from Tijuana," where she has been invited to participated in a church-supported migrant-aid project, Arellano said.

Saul did not speak to reporters and spent most of the news conference in a Tijuana hotel hugging his mother or hiding behind her.

Arellano had lived in the United States illegally for several years when she came to the attention of immigration authorities. She took sanctuary at a Chicago church for about a year in defiance of a deportation order, but left in August and was arrested and deported after giving an immigration speech in Los Angeles.

Saul has spent the last year appearing at rallies across the U.S., on television and at meetings with lawmakers, and on Wednesday participated in a protest of about 150 activists inside the halls of the U.S. Congress.

But he has often seemed distracted and ill-at-ease in the media spotlight, and his role in immigration activism had raised questions because of his age and his separation from his mother.

In Mexico, he will apparently participate in a project to teach English to local children. Arellano said Saul originally wanted to stay in the United States, but after meeting his grandfather and cousins on a previous visit, he became happier at the prospect of moving to Mexico.

They will live at her sister's home in Maravatio, Michoacan, she said, until they can fix up an abandoned home there owned by her parents