DES MOINES, Iowa (KTRK) -- A Texas man was sentenced to 35 years in prison on child pornography charges.
Mark Barnwell, 36, was found guilty of using fake Facebook profiles to meet young girls.
Barnwell would pose as a modeling agent online, then threatened the girls to get them to send him nude photos.
"Children are the most vulnerable," said Special Agent in Charge Nate McLaren. "It's easy to get passionate about these cases when you have children."
Investigators say methods like this are a nationwide concern as children continue to use smartphones and other mobile devices.
Police say the best way to protect children is to monitor their online use.
Texas man sentenced after using fake Facebook profiles to meet young girls