Proof once again
If you actually have something to hide, like your whereabouts as a professional killer, having something on you that can link you to a crime scene is exactly the thing you should avoid.
So, to all professional hitmen out there : when you're on the job, take nothing electronic with you. Have a normal watch, without any Internet connection. Lose the phone, it is literally a legal snitch. If you are into physical fitness, by all means use your Fitbit, but not when going anywhere near a potential target. On the contrary, give it to a friend who'll run for you while you take out a target, giving you a potential alibi.
And use a GPS that cannot talk to anything. Erase all location history when you're done with your surveillance. When you go on the hit, you should know the area well enough to not need it because if something goes wrong and you're on the run, you won't have time to look at a screen to know where to go.
Think, people, think.