The Wasted Womanizer - The Hot Dog Detective (A Denver Detective Cozy Mystery), #23

When Defense Lawyer Jerry Baker asked former Police Detective Mark MacFarland to help defend Anita Faraday, the wife of Tom Faraday, MacFarland thought proving her innocent would be a piece of cake. Tom had been the head of a polyamorous family, and the killer was probably a disgruntled member of the family.  While it was usually the spouse, as Detective Lockwood kept telling him, in this case, there were a lot of other potential spouses. Tom Faraday had been poisoned.
The poison was unusual. It was a toxin secreted by a species of newt not found in Colorado. Solving this murder should be easier than most. All he had to do was find the person who could put newt poison into a bottle of wine. While MacFarland had several potential suspects, nothing tied them to the weapon used to kill Faraday. This was clearly one of those times when MacFarland, in order to solve this case, would have to think out of the box.