Who the heck is Lawrence L. Blaine? I can't provide a definitive answer. One site I looked at credits the book to Robert Silverberg. Another says it's a collaboration between Silverberg and Eleazar Lipsky. I tend to believe the latter, since Lipsky was an assistant D.A. in New York and also legal counsel to the MWA for many years. Lipsky was a well-known writer in his own right, having had Hollywood success with Kiss of Death (based on his 100-page manuscript) and The People Against O'Hara (based on his novel). He wrote a number of others, too.
So why this collaboration with Silverberg (if that's what it was)? And why did it get published in paperback with a generic cover that has nothing to do with the contents? Good questions, I think, but I have no answers for them.
It's a very entertaining book. It's a western, a mystery, and a courtroom drama all in one. A woman is murdered, and, as the cover tells you, "the son of the territory's richest and most powerful man" is accused. Jake Kilgore, assisted by Clem Erskine, a young man who's newly arrived in town to serve as Kilgore's clerk is hired. All the evidence points to the guilt of Kilgore's client, but Kilgore, a man with a big ego, is sure he can avoid a conviction. There's a lot more going on than Kilgore knows about, however: old secrets, a family that shows there's no fun in dysfunction, powerful forces that align to get a conviction. And someone's leaking information to the sheriff, each piece of it more damaging than the one before.
My guess would be that the book was intended as the first in a series. If that's true, however, the series was not to be. This standalone is worth looking for if you're interested in a western that's a good bit different from most you're likely to find.