Once upon a time, a rich old guy was stabbed in the drawing room of his estate. (This is a British story, by the way.) He was discovered by his nephew, whose cries of alarm brought the rest of the family running. As they crowded the doorway to the drawing room, the nephew knelt at the old man's side to hear his last words. The man rasped a few syllables and expired.
Soon the police detective arrived and assembled all the suspects — the old man's relatives and potential heirs — in the library. One by one he questioned them about where they'd been when the murder occurred. Each had an alibi: they'd all been playing bridge together in the parlor. Only the nephew who had discovered the dying man had anything to add.
"I know who killed my uncle," he said confidently. "It was someone named Jack Hughes."
"How do you know?" asked the detective.
"My uncle's dying words were 'Jack Hughes,'" replied the nephew. "We all heard him say so. Clearly he was naming his murderer. So now you have only to find this Jack Hughes and the mystery will be solved."
The detective asked the family if any of them knew someone named Jack Hughes. They did not, nor did any of the staff at the country estate. But the nephew remained adamant about what he had heard.
The detective mulled this over quietly for a few moments, then arrested the nephew and sent him away in handcuffs.
"But why?" chorused the family.
"Because that young man killed his uncle," the detective said. "He must have snuck into the drawing room, stabbed the old man, then slipped back into the parlor with the rest of you. When he pretended to come looking for his uncle, he expected to find him already dead. But his uncle wasn't dead, and he said words all of you could hear."
"Yes, he said Jack Hughes," replied the widow. "But that's not our nephew's name."
"That's not quite what your husband said, ma'am. I think he said 'J'accuse' — a French phrase meaning 'I accuse you.' He knew who had stabbed him and said so with his last breath. Your nephew was clever enough to try and reinterpret the words — but not clever enough to elude the law!"
And the triumphant detective swirled his cloak around him and left.
Or something like that.