Fiston Ngoy, 35, was arrested and charged in the horrifying attack on Wednesday on board a Southeastern Pennsylvania Transportation Authority (SEPTA) train near the suburb of Upper Darby.

Ngoy entered the US on a student visa in 2012, but remained after the visa was terminated in 2015, and was protected from deportation by the immigration system despite multiple convictions, according to Fox News.

Court records show that Ngoy had multiple arrests and two misdemeanor convictions, one for controlled substances and one for sexual abuse.

He pleaded guilty to the sex charge in 2017 in Washington DC and was sentenced to 120 days in jail, and was then placed in immigration detention in January 2018.