richie sambora is about to be quizzed by police over claims he ` threatened to kill ' his former fashion designer lover and business partner .
she is a childhood friend of kim kardashian .
police in the wealthy los angeles suburb of calabasas confirmed sambora is a ` person of interest ' in an active investigation into criminal threats .
their joint venture collapsed at the last moment and nikki went out on her own .
rock star is believed to be on vacation in bora bora with his ex-wife heather locklear and daughter ava .