denlinger give them the green.he spring of 2018, and by the summer, they had sent us report. and they said, that they had found the relative of our killer. >> a relative of your color? >> yeah. they hypothesized that she was a second cousin, what's removed, from our color. >> well there's a headline for you guys. >> yeah. >> that person related to the killer was a woman living in vancouver, washington. now the trick was to build a family tree to see if police could link a family member to cedar rapids in 1979. denlinger reached out to the woman, she agreed to answer all his questions. >> we have to start building her family tree. >> denlinger trace the woman's family treat back to the early 18 hundreds. >> so, you're looking through all historical records, census data -- >> absolutely. >> tombstones? >> tombstones. anything we can find. >> created four branches of the family, going back to great, great grandparents. the first branch lead to someone living in ohio. denlinger got a dna sample. >> we sent their dna ba