Partners in Crime by JA Jance

 This is an old book by JA Jance featuring the "stars" of two of her regular series--JP Beaumont and Joanna Brady. The action starts in Arizona, where an up-and-coming artist is supposed to have her first show in a gallery--till she turns up dead under suspicious circumstances. Then the gallery owner turns up equally dead. Joanna is investigating the first death when she gets a call from Washington state saying an investigator named Beaumont is coming to town because the first victim was a witness in a big trial that was coming up and had been put in witness protection to keep her safe. Joanna is not thrilled to have an out-of-town cop interfering until she eventually realizes JP is a good cop and could actually help. 

I like both Joanna and JP so I enjoyed this story. It had some interesting twists along the way to finding out who did it.