According to police, Bertha Avalos, 47, stole Todrick Hall's iPhone 5 during his visit to Hazard Elementary School.
Hall, who was on the "American Idol" show in 2010, was signing autographs when he placed his phone on a school bench behind him. That's when, police say, the woman allegedly stole his phone.
Hall later discovered his iPhone case, along with $400, was missing. He used the "Find My Phone" application on the device and tracked it to a grocery store in Garden Grove.
Hall said he recognized a student from the elementary school at the grocery store and approached him.
"He didn't have the phone and he genuinely looked like he didn't know where the phone was," said Hall. "Lo and behold, we found out it wasn't the student who stole the phone it was the mom who stole the phone."
Avalos surrendered the property to Hall but was later arrested and booked on suspicion of grand theft.