Two of his Indian associates were also held.
The arrests were made by the Mamallapuram police following a complaint from one of the inmates of the orphanage, who escaped and registered a complaint with the Pondicherry police, who tipped off their counterparts in Mamallapuram, Deputy Inspector General of Police, Chengalpattu Range, Jankhid said on Friday evening.
It was alleged that Williamus sexually abused the children after giving them biscuits laced with intoxicants.
There were a total of 42 children in the orphanage, 'Little Home', being run by him for the past five to six years.
The majority of the children had been handed over to their relatives, the DIG said.
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