They're asking for source code to a program. AIUI, the input data that was supplied to that program will contain or not contain those DNA (fragments) in a fairl

They're asking for source code to a program. AIUI, the input data that was supplied to that program will contain or not contain those DNA (fragments) in a fairly simple format. It is of course possible that the program doesn't emit a detailed enough report. That it says "match found" without saying where in which files it found a match. But it's also possible that it does say where, in which case the presence of the needles can be verified easily, even if the method used to detect that those were relevant needles rather than irrelevant straws isn't specified. Either way, rejecting an unknown algorithm because it's unknown is wrong. What matters is whether the output can be checked by others.