Any of these capture your fancy?:
http://www.amazon.com/Deep-Politics-Death-Peter-Scott/dp/0520205197/ref=cm_lmf_tit_40
http://www.amazon.com/Regicide-Official-Assassination-John-Kennedy/dp/1591482976/ref=cm_lmf_tit_6
http://www.amazon.com/Brothers-Hidden-History-Kennedy-Years/dp/0743269195/ref=cm_lmf_tit_11