Tandem S06E10 - En eaux troubles

Shots sounded at the edge of the Mejean pond. A woman agent of the OFB (the French biodiversity office) is found dead. The murderer is not far away, you have to be quick. The gendarmes understand that the victim was investigating around the pond. Leah is convinced that she was looking for something, but what ? It then sends divers, which takes out a second body. Who is this new victim who has not been declared missing ? What is the relationship between her and the grievor ? Were they killed by the same person ?