The Last King of Texas — Rick Riordan

When a controversial English professor is found shot to death, Tres Navarre--P.I. and Ph.D.--is the only local academic crazy enough to accept the emergency opening at the University of Texas at San Antonio. Police assure him they already have a suspect, so while they wrap up the open-and-shut case, all Tres has to do is teach three classes, grade on a curve ... and walk in a dead man's shoes. It should be an easy assignment--but one thing Tres doesn't do is easy. When the evidence in the case starts looking a little too perfect, when the killing doesn't stop, Tres takes on some extracurricular research into the heart of an assassin--and lands in a high-stakes game of gangster honor on the darkest streets of San Antonio's West Side....