The one common denominator tying the bequest, Sam's death, Micco's keys at the refuge, Rory, and Frank is Martina.
When Sam's bad finances came to light, I suggested he might have planned challenging the will. All he would need to question is her mental state or show undue influence. Martina could have pressured Rory and Frank to make statements against Micco and she had ready access to the refuge and the keys. Sam would have readily met her at the refuge unsuspecting her motive.