Abstract: Computer systems and computer-implemented methods for forensically investigating a target dataset including a target file by comparing the target file to a source file are provided. The method includes performing a preliminary matching operation. The preliminary matching operation includes performing at least one of a file size matching operation, in which a target file size is compared to a source file size, and a sub-hash matching operation, in which a target file sub-hash is compared to a source file sub-hash. A sub-hash is a hash value calculated using a subset of data from the file. The method further includes performing a full hash matching operation if the preliminary matching operation identifies a preliminary match. The full hash matching operation includes generating a target file full hash value and comparing the target file full hash value to a source file full hash value.