A registered sex offender was indicted by a federal Grand Jury Thursday on child pornography charges.

Robert Knappenberger, 40, was convicted of rape 20 years ago, according to state records.

On Thursday, Knappenberger was charged with using a child to produce child pornography and distributing the images over the Internet, said U.S. Attorney Zane David Memeger.

Knappenberger, of Boyertown, also faces a counts of sexual exploitation of a minor by a registered sex offender, possession of child porn and three counts of distribution.

If convicted, he would be eligible for a mandatory 35 years to a maximum of 200 years in prison and fines of up to $1.5 million.

The case was investigated by U.S. Postal Inspection Service and is being prosecuted by Asst. U.S. Attorney Michelle Rotella.

Contact staff writer Sam Wood at 215-854-2796 or samwood@phillynews.com.