BATAVIA, Ill. - A shaken father in Illinois has taken to social media to warn parents about a feature on a popular app used by kids.

Brad Summer said his 7-year-old daughter used the app to "connect with her cousins and make goofy duets of songs together."

The daughter, who uses the app on her parents' devices, has accepted requests from friends of friends before.

"I never thought of someone pretending to be 9 to gain access to my child," Summer wrote.

He posted screenshots of the messages sent to his child to warn others.

What begins as seemingly harmless back-and-forth between children suddenly turned sinister, when the stranger asked the 7-year-old girl to send pictures without her shirt on, saying it will be a secret between them.

Summer said he is proud of his daughter for knowing to tell her parents about the messages.

The last screenshot shows Summer messaging the stranger back, saying: "I am her father and I am a police officer. We have documented your IP address and location. I recommend that you refrain from any further contact."

He reported in an update that officers indeed found the IP address of this person, and submitted a subpoena to to freeze all records pertaining to them.

Summer finishes his warning by thanking those who have shared the message.

"By sharing, we have reached and informed so many families to be on the lookout for these pedophiles," he wrote. "I say that doing nothing, accomplishes nothing. Doing something, at a minimum gives us hope."

This story originally appeared on KCCI’s website.