Re: The Origin of James Mitose's Kenpo?
Going by his first book, I think it is most likely that he got a LOT of his information from the two books you mentioned. Many of the techniques etc. are reproduced including actual photographs from these two books.
Now, having said that, what Mitose was teaching before he decided to make his book is less clear. The reports of his students seem to indicate that he taught a very karate-like martial art with a lot of drill and one-punch kill technique etc. and the Nihanchi Shodan kata. Where he learned that is hard to say. Someone mentioned someone named Tanamaha (whom I have not heard of before, but was ostensibly a student of Choki Motobu). His Jujutsu techniques could have been learned from Okizaki since, I believe he taught in the same gym as Okizaki did.
Mitose seemed unclear on what to actually call his martial art. Many different names including karate were used by him.
1st degree Black Belt in Kajukenbo (Original Method) under Prof. John Bishop
Bishop's Kajukenbo Academy, Diamond Bar, CA