A Hyattsville mother thought she was in good hands with her nanny. She hired her based on a referral from a relative and an au pair company.

Aza Hrnjic, a 22-year-old Bosnian, had been staying with her family watching her three kids. But in June, she noticed something wasn't right. Her son was crying and didn't want the nanny around anymore.

Once she started asking questions, she found out the woman she had trusted with her children had a dark secret. She had allegedly been showing porn to the kids.

The mother contacted police.

"Based on the information we have, there are indications that she displayed porn images to the children, and also possibly through the use of a webcam displayed nude images of children," said Chief Doug Holland of the Hyattsville Police Department.

Aza was arrested Thursday and charged with several offenses, including child abuse and having child porn on computers.

"It was totally unexpected-- I would have never expected something like that would happen," said the mother, who asked FOX 5 to maintain her anonymity due to the situation. "You can't judge somebody by what they looked like-- she seemed like a nice person."

"It's just serves as a reminder to all parents-- please don't take for granted anything at all when leaving your children in the care of trusted friends, neighbors or so-called professionals-- you can never be too careful," says Chief Holland.

Police say at this point there is no indication that there are more victims, but investigators want anyone who used her as a nanny to contact them. Aza is currently in jail on a $350,000 bond.