An approach that has shown promise in solving both of these difficulties is called Y-STR analysis, based on the male Y chromosome. An NIJ-funded pilot study of Y-STR DNA profiling by Ballantyne and his colleagues offered hope for a solution to the problem of analyzing postcoital samples collected more than three days after the incident.[3] His team was able to obtain complete Y-STR profiles on samples collected as many as five days after coitus and a partial profile at six days.