In context - a report on the news today, and other similar reports in recent months - it tends to be used of cases that happened a while ago, rather than those that are somehow especially significant (record-breaking? innovative? the cause of the fall of a government? it's hard to come up with measures for significance in this context that aren't at least a bit queasy-making in themselves, since they imply other cases and victims of abuse to be relatively "insignificant"). But I take your point about historic/historical: that ambiguity was one part of what threw me.