I agree with Ben. As presented, there is no probative value. Even if combined with other matching test kits in a triangulation group, I would personally consider it suspect as evidence. Discounting the fact that a single, small segment match can't be used as validation of a distant ancestor (at these dates we'd be dealing with the people tested probably being in the range of 6th to 9th cousins--very difficult if not unrealistic to attempt to validate with autosomal DNA using the current technology), there's a problem with the location of the 8.6cM segment itself.
There are areas along some chromosomes we have begun to identify as what are colloquially called phenotypical "pile-up regions." These are places where an inordinate amount of the population share the same alleles. The quickest example is a stretch along chromosome 6 called the HLA region. This area relates to some of the human autoimmune functions. Obviously, mutations to autoimmune functions are NAGT (not a good thing ;-) for survival of the organism, so that region looks very much like it has for a very, very long time.
On chromosome 15, two such regions have been identified: assuming GRCh37, from bp 20,060,673 to 25,145,260 and 27,115,823 to 30,295,750. You can see that the small segment at 24,410,624 to 27,186,206 overlaps both those regions. Generally speaking, I would discount that segment even in a triangulation group without additional information.
