This Chess problem comes from Arturo Pérez-Reverte's "La tabla de Flandes", a murder mystery novel about a XVth century painting called "The Chess Game", which hides a painted-over Riddle : "who killed the knight" ?
 

That enigma always reminds me of that time when Batman went missing for several weeks, after a brutal fight against the Joker and his henchmen (and his henchwoman). The Joker had hidden in a dangerous industrial area, and during a confrontation with Batman and his allies, a member of Joker's gang caused a massive explosion that left nothing of Batman but his cape and cowl.

The Police and Batman's friends investigated to find out who killed the Dark Knight, but with no success.
 
The Chess board below, adapted from Pérez-Reverte's problem, gives you the opportunity to show you're a better detective than Batman's allies, and find out which white-faced criminal earned Batman's cape and cowl.

What you need to know :

1) Obviously, Chess rules were followed.
2) Blacks would take any chance to get the White Queen.
3) Whites just moved.

Knowing this, who, and what move, killed the Dark Knight ? Remember a Help Quiz is available.