Nah, they have a shawl with no provenance that someone found in an attic and they have just decided it might have belonged to one of the victims.
Supposedly the DNA match with the victim’s descendant was 99.99%, IIRC.
I can’t speak to the accuracy of the Mitochondrial DNA match as that suppoosedly casts a wider net.
Of course, they could always just be lying. Wouldn’t be the first time that happened on tv.