Legal Question in Criminal Law in California

No, you're not being clear, because you're not understanding the system or process.

Police either find actionable things, like child porn, ON your phone or not. They don't 'hack' into anyone else's, except: IF they really, really want to 'get' you, your problem would be that even if actionable things were earlier 'deleted' from your phone, it is not actually erased and gone, but is still possibly 'forensically' recoverable [depending upon the phone & operating system], for quite some time until being overwritten in storage memory. Plus, if you use cloud storage backup, in addition to normal phone provider backup such as Verizon, it is still also in your account servers in those places. Plus, your wireless service provider's main servers also have copies of every message and call to/from you that are recoverable by warrant -- the same with emails through all the major providers like Yahoo, Google gmail, etc.

Police wouldn't be able to go to someone else's account that they see messages to/from without a warrant specifically detailing to a judge WHAT they know they will find on that account, AND that it was sent by you. They wouldn't have such detailed info unless they already accessed the actionable things on YOUR phone or backup servers. They then could pursue charges against the other party, assuming we are talking actionable matters like child porn.

The take away for you should be an understanding that you, we, have no remaining expectation of privacy in our communications, phone, text messaging, email or web browsing.

Now, if you need the help of experienced criminal defense counsel in SoCal, feel free to contact me at 714-421-2501