Litman says that Kostikov was a former "client" and that he died in 2002. Litman also says he arranged the book deal for Nechiporenko but doesn't mention, as far as I can tell, what happened on the planned book by Kostikov. He also says that Kostikov et al. did meet Oswald. His "biography" - such as it is - on Kostikov is here: https://medium.com/@bdlitman/col-valery-vladimirovich-kostikov-kgb-aka-comrade-kostin-33f7d730adb1
