"Monday, Tuesday, he called in for a sub," said Ruelas' brother, Alejandro. "Wednesday, no call, no show."
Ruelas, who has been teaching for 14 years, has had nearly perfect attendance.
According to his brother, Ruelas saw their sister Sunday and spoke with their father Monday night.
At his home, his car was gone, his doors were locked and nothing was touched inside.
"His bikes were there, his camping stuff was there," Alejandro Ruelas said.
Friends and family said he was feeling stressed about work and a recent teacher evaluation printed in the Los Angeles Times.
"Overall, the whole mood, the kind of attacks against teachers, it has us pretty tense," said Jose Vergara, who works with Ruelas at the school. "
"He kept saying that there's stress at work," Alejandro Ruelas said.
Alejandro Ruelas said his brother is a teacher who goes above and beyond.
"Be strong, we're here for you," said Alejandro Ruelas as he wept. "We know the truth. We know how good of a person you are and you've always been helpful to everybody."
Anyone with information on the whereabouts of Rigoberto Ruelas is asked to call South Gate police at (323) 563-5436.