What secrets did Finn keep from Joe during his lifetime in the novel, Hope Never Dies: An Obama Biden Mystery?

Finn's death took place in suspicious circumstances that trigger Joe into an unofficial investigation, which in turn leads him to disquieting secrets in Finn's life. These secrets are mostly associated with Finn's connection to the illegal drug trade - specifically, his participation in the movement of drugs from one location to another. He undertook this activity in order to make money to pay for his wife's medical care, an aspect of his life and identity that suggests, on one hand, love and loyalty; on the other hand, desperation.