WARREN, Mich. -

Mark Brittan, 36, who has taught at schools across Metro Detroit, is charged with possessing child pornography.

The police investigation began back in April when Brittan was a substitute teacher at McKinley Elementary School in Warren. Going against the district's policy, Brittan took pictures of a female student in the classroom. The student, feeling uncomfortable, told her parents who then contacted the Van Dyke Public Schools district.

Watch: Victim's mom speaks about teacher facing child porn charges

"When we found out what had happened, the reason that was given to us was that he just does this to remember the student's name. I said no, something's not right," said Joe Pius, of the school district.

Brittan, who was hired through a company which places substitute teachers, was fired. Police then found images of child pornography on his home computer. At this point, none of the pictures found are believed to be McKinley students.

"It's very disturbing. Obviously, this person flew under the radar," said Pius.

Brittan may have been teaching a 3rd grade class at the time of the April incident. Police believe he only took pictures of the one female student.

The district gives the girl credit for speaking up. Otherwise, there is a good chance this man could still be in the classroom.