The bride and her sister are identified as Croatians, but the Cyrillic alphabet which is identified as the source of the killer's mark is not used in Croatia. Cyrillic is used for the Serbian language (although the two languages are mutually intelligible).
Maura repeatedly identifies the Cutthroat's mark as a "...Cyrillic letter 'K'...". However, of the Cyrillic letters that have the same forms as Roman letters (which 'K' is one), it is impossible to identify a single letter as Cyrillic without the context of other letters unique to that alphabet. Similarly, it would be impossible to determine whether a lone "P" was a Roman 'P' (representing the sound
) or a Cyrillic 'P' (representing the sound [r]).
) or a Cyrillic 'P' (representing the sound [r]).
Maura says the blue substance in the wound is Methyl Isobutyl Ketone. It is known as MIBK for short and is a colorless sweet smelling solvent used in paints and paint thinners that is colorless and evaporates away completely so it could not leave a residue of any kind, especially not blue.
Cutthroat tosses his hostage aside leaving himself vulnerable to being shot, which he was. It is illogical, yet it happens over and over.