How could Pell not have known of child abuse?

This will be the week that Cardinal George Pell, a pillar of the Catholic Church in Australia for much of the last four decades, and now the third most powerful figure at the Vatican, faces the Royal Commission into Child Sex Abuse.
Sadly he will not be be giving his evidence in Australia, as – despite being capable of continuing his normal work running the Vatican finances – 24 hours in a Qantas First Class is quite beyond him.

http://www.smh.com.au/comment/now-thats-progress-20160226-gn4dqu.html