How are these things audited?
And there is another factor to consider - not all engaged as snipers regard the number of deaths at their hands as something to be recorded at all, let alone applauded. Conscience and fear are powerful deterrents to publicising such slaughter. We will never know the identity of the "world's deadliest sniper" and can be reasonably sure that whoever lays claim to the title, or has it conferred upon them, assumes the mantle ahead of others who would only be too glad the recipient has drawn attention and analysis from their own activities as specialist killing machines.