A 56-year-old Chester County man already facing state child-sex charges was indicted Thursday in federal court in Philadelphia with making child pornography.

In March, Pennsylvania state police made a public plea for any alleged victims of Robert Dean Caesar to contact authorities as part of a widening investigation. Caesar, who is originally from Philadelphia, has also lived in Western Pennsylvania, Colorado, and Florida.

The state police said they received an online tip in January that Caesar was purchasing used boys' underwear and bathing suits through eBay.

Soon afterward, an allegation was made that Caesar sexually abused two boys in the Oxford area from 2015 to 2017, state police said. Caesar was arrested and charged with sexual assault. A third boy surfaced with an allegation of sexual assault in 2016, and Caesar was again arrested and charged.

Authorities executed a search warrant on his electronic devices and found approximately 100,000 images and videos of child pornography, state police said.

In May, state charges were filed in Western Pennsylvania against Caesar, alleging he sexually assaulted two boys in 2005, when he lived in Cranberry Township.

The criminal complaint said the two boys, ages 9 and 14, told officials that Caesar had sexually assaulted them, the Cranberry Eagle reported.

One of the boys said that he mowed Caesar's lawn, and that Caesar invited him into his basement and asked the boy to model underwear and bathing suits so he could take digital images "to see how they fit," the Eagle reported.

Police searched Caesar's home and found 76 pairs of boys' underwear.

In the federal case filed Thursday, Caesar faces a maximum of 100 years and a mandatory minimum of 15 years in prison if convicted.

Federal prosecutors offered no specifics except for dates of offenses. On Sept. 17 and Dec. 30, 2017, Caesar allegedly manufactured child pornography. On Dec. 20, 2017, Caesar allegedly received child pornography. And on Jan. 18, he allegedly possessed child pornography.