(CNN) A Pennsylvania man has been arrested and charged with sexually abusing children at an orphanage he founded in Kenya, federal officials said.

Gregory Dow, 60, was taken into custody Friday at his home in Lancaster County, Pennsylvania. He started a home for orphaned children in the east African nation in 2008, and allegedly abused the minors under his care for years, according to the US Attorney's Office in the Eastern District of Pennsylvania.

He was indicted on four counts of engaging in illicit sexual conduct in a foreign place.

The alleged abuse occurred between October 2013 and September 2017 at the facility he founded in the rural area of Boito. He took part in or tried to engage in illicit sexual conduct with four minors under his care at the home, authorities said. Investigators have said there may be more victims but tracking them down in Kenya has been a challenge.

"The defendant purported to be a Christian missionary who would care for these orphans who called him dad," the statement said. "But instead of being a father figure to them, he allegedly preyed on their youth and their vulnerability."