The Judge Advocate General's Corps are naval lawyers. The JAGs
were established within the Department of the Navy in 1967 at which time these
specialized military lawyers became a distinct professional group within the
Navy, similar to physicians and chaplains.
Mark Cohen served as a JAG for 20 years. His next book, Bluetick Revenge has just been published.
The Fractal Murders is one of those relatively rare self-publishing success stories. Mark Cohen worked with three agents who failed to find a publisher for it, so in 2002 he published it himself. Two years later he'd sold a few thousand books and got plenty of word of mouth coverage - at which point Mysterious Press, a division of Warner Books, bought the rights and republished it.
Interesting Link: More than you probably want to know about fractals!