LOS ANGELES (CBS NEWS)-- A 24-year-old Los Angeles woman was arrested last week in Mexico after authorities say they found her grandmother slain and wrapped in plastic and a blanket.

Sarah Montoya was arrested Wednesday and appeared in court Friday in connection with the death of her grandmother, Paula Montoya, 64, reports CBS Los Angeles. Paula Montoya was found strangled in a bathroom of her home July 21, wrapped in plastic and a blanket, Los Angeles County Sheriff's officials said at a news conference Monday. She also had broken ribs and a bruise on her head, the station reports.

Authorities had issued an alert for Sarah Montoya and her four children, ages 1 through 9, who they believed were last to be with the slain woman. According to the Los Angeles Times, officials received a tip that the woman was in Mexico and was planning to cross the border back into California. She was reportedly arrested at the Otay Mesa border crossing and taken into custody by the U.S. Marshals. Her children were with her, unharmed.

A motive for the attack is unclear, but according to sheriff's officials, Sarah Montoya confessed, telling investigators she "snapped."

Sarah Montoya was arraigned on Friday after investigators filed with the Los Angeles County District Attorney's Office for one count of murder, the paper reports.

Paula Montoya was an active member of her local church, a grandmother and great-grandmother, sheriff's officials said.