As The Times reported in August, the blacklist often didn’t work: Men expelled for alleged abuses slipped back into the program, only to be accused of molesting again. Now, a more extensive review has shown that Scouts sometimes abetted molesters by keeping allegations under wraps.

In the majority of cases, the Scouts learned of alleged abuse after it had been reported to authorities. But in more than 500 instances, the Scouts learned about it from boys, parents, staff members or anonymous tips.

In about 400 of those cases — 80% — there is no record of Scouting officials reporting the allegations to police. In more than 100 of the cases, officials actively sought to conceal the alleged abuse or allowed the suspects to hide it, The Times found.