Rochelle Baxter, an up-and-coming artist in Cochise County, Arizona, dies mysteriously the night before her first gallery opening gala. The fact that her death is probably a homicide isn't such a surprise to Sheriff Joanna Brady. But Rochelle Baxter was a former Marine M.P.-living under a Washington State witness protection program. Outraged that his star witness in a private-prison corruption scandal has been rubbed out, the Washington State attorney general sends investigator J.P. Beaumont down to Arizona…