On a Friday morning three years ago, nurse Christine Banfield was fatally stabbed in her bedroom. With her was Joseph Ryan, a stranger who was shot dead.

The nurse's husband — IRS special agent Brendan Banfield — told authorities he killed Ryan after the man attacked his wife.

What prosecutors say actually happened inside the home was the result of something far more convoluted and sinister — a deadly catfishing scheme that was motivated by an affair and relied on a fetish website to lure an unsuspecting man to his death.