A father scanning a folder of recently deleted photos on his son’s iPad triggered an investigation that led Thursday to felony sex-related charges against the boy’s middle school lunch lady.

The Dakota County attorney’s office charged Krista Ann Muccio, who turns 42 Friday, with one count of communication with a minor describing sexual conduct and one count of possession of pornographic work involving minors for offenses that allegedly occurred last year.

Muccio was a lunch assistant in the cafeteria that serves Simley High and Inver Grove Heights Middle School students. It was there she met a 15-year-old student with whom she exchanged sexually explicit photos and conversations online, she told investigators.

An Inver Grove Heights district spokeswoman said that Muccio worked for the district from March 2014 to Dec. 4, 2014, but wouldn’t explain why she left.

According to the charges, the student’s father called police in November and the boy told investigators he began exchanging photos with Muccio on Instagram in June 2014. In an interview with detectives, Muccio admitted to sending the student “pictures of stuff online and girls in bikinis” and that the boy sent photos of his genitals in return.

A search of Muccio’s Instagram account and cellphone revealed that she was following the student’s profile and they had exchanged sexually explicit messages.

Muccio is scheduled to appear in court on May 4.