The Day of the Jackal question

I'm not sure what is confusing about the ending to you, but I'll guess about it and try to answer.

I'm going to add a spoiler tag here, just in case someone who hasn't read the book comes by. I'd hate to spoil the story for them.

(view spoiler)[
At the end, de Gaulle moves his head a little bit, so the Jackal's shot misses. At the same time, the police break into the room and shoot the Jackal, killing him. Later, the intelligence / police are searching the apartment of the guy that they thought was the Jackal, Charles Calthrop, and he returns home, surprising them. It turns out that he really was on vacation in Scotland. He wasn't the Jackal after all, despite all the clues they thought led to him. The final part is the question, if the Jackal wasn't Charles Calthrop, then who was he? No one knows. He's buried in an unmarked grave, and listed as a foreign tourist. No mention of him trying to kill the president. (hide spoiler)]
Hope this answers your question!