A.C. sends in this opening sentence from a story in his local (NZ) paper:
The former lover of a murdered British jeweler was in his bed when he and his new girlfriend arrived at his villa on the Costa del Sol.
The players on the referential scorecard are:
(1) the former lover
(2) a murdered British jeweler
(3) his bed
(5) his new girlfriend
(6) his villa
In the end, the co-reference chain is easy: (2)=(3)=(4)=(5)=(6). And once you get that "his bed" belongs to the "murdered British jeweler", the rest of goes pretty smoothly.
But it's natural to start (1)=(3) — "the former lover [...] was in his bed", and then things get tangled up quickly. The former lover was in his bed when he and his girlfriend arrived at his villa? Say what?
As a famous computational linguist once said to me, "CoRef is hard. Or really, it's easy except when it isn't."
The obligatory screenshot (OK, page image):