  Digital forensic investigation has become more challenging due to the rapid
growth in the volume of encountered data. It is difficult for an investigator
to examine the entire volume of encountered data manually. Approximate Matching
algorithms are being used to serve the purpose by automatically filtering
correlated and relevant data that an investigator needs to examine manually.
Presently there are several prominent approximate matching tools and technique
those are being used to assist critical investigation process. However, to
measure the guarantees of a tool, it is important to understand the exact
requirement of an investigator regarding these algorithms. This paper presents
the findings of a closed survey conducted among a highly experienced group of
federal state and local law enforcement practitioners and researchers, aimed to
understand the practitioner and researcher's opinion regarding approximate
matching algorithms. The study provides the baseline attributes of approximate
matching tools that a scheme should possess to meet the real requirement of an
investigator.
