LOUISVILLE, Ky. (WDRB) -- Police say they arrested a man who was preying on a 10-year-old girl.

Indiana State Police troopers and Washington County Sheriff's deputies arrested 44-year-old William Knight Tuesday in Pekin, Ind., at his mobile home. 

"I saw them all line up, and one-by-one come up the road and all gather around the circle here," said Tammy Goss, who lives nearby. 

During an investigation, the say they discovered he was using Facebook to chat with a 10-year-old girl and was encouraging her to touch him in a sexual manner.

"We've got a mother that was very astute. She was aware of what was going on with her kids. She was able to locate some messages on a social media site," said Indiana State Police Sgt. Jerry Goodin. 

Police say Knight and the girl knew each other. 

According to a probable cause affidavit, he said things like "have you ever been with a man" and "do you know how to kiss." 

"We have an adult that's preying on a small child. That's very disturbing," Goodin said. 

Police say nothing physical happened between Knight and the girl. Goodin says this case should serve as a wake up call about who kids can come into contact with online. 

"You need to make sure that you know what your child is getting on to. You need to check the apps that they are downloading on their phones. You need to check the programs they are downloading on their computers because I'm telling you - there is no child that is immune to being a victim," Goodin said. 

Police say at this point, they don't think Knight was communicating with other kids online, but they are still looking into it, which is standard procedure. 

Knight is being held at the Washington County Jail and is expected to appear before a judge Thursday morning. 

Copyright 2016 by WDRB News. All rights reserved.