A Girl, Her Boyfriend, Her Ex-Boyfriend - Jail???

you are wrong.

the more serious charges may be difficult to prove, but prosecutors aren't stupid and the courts aren't like on CSI. you don't need dna or fiber evidence to convict people of these types of crimes. if you know about this and the ex-bf knows about this, then so do hundreds of other people. if what you say is accurate and especially if the phone calls you mentioned were of a threatening nature, the da will have no problem bringing a case.

luckily for 'jack', california has a problem actually going from building convincing cases to putting people in jail. he may just do county time.