If this was a murder, this would actually be very hard to prove who did it. Anyone in the world with an internet connection and the MyTesla login to the car could have done it. How do you prove who pressed the button‽
Before I begin, thanks for making and maintaining a great app.
Concerning the question above, it's worth noting that a prosecutor does not have to prove who pressed the button, per se. The prosecution need only convince a jury (I hesitate to say "of one's peers") that a given defendant is guilty.
With the usual disclaimers and caveats, I'd start by reviewing logs from the car owner's phone. Location and IP address would then be matched with the car's logs and possibly with information from the app's servers, depending upon who got served with what.
The analysis could exonerate or, more to the point, *not exonerate* the owner. It's the latter case that would then get spun by the prosecution to "make the rich Tesla driver pay". Not to mention the follow-up civil trial with a lower standard.
One does wonder about the wingnuts who lurk in the shallow end of the gene pool, screwing things up for everybody. See recent Danish video of backseat driving, or, inevitably, some video of someone who tries to Summon their car from a greater-than-intended distance, in the process managing to run over over the neighbor's cat or body part. Or worse.
Gotta love the bleeding edge of applied technology, relatively speaking.