Conservation geneticist Christy Edwards never expected to use her knowledge of plant phenotyping to help solve a murder. The experience seemed more akin to a script of “Law and Order” or “CSI”: A young wife and new mother disappears, the investigators suspect her husband of foul play, and they just need the evidence to prove it. Instead of blood, mud and juniper needles become the focus — and Edwards and her colleagues at the Missouri Botanical Garden rush to collect samples and analyze over 100 trees around Mengqi Ji’s burial site, evidence that ultimately ties her husband to the crime.