online.wsj.com/article/SB10001424052748704025304575284501726547986.html

What could be a more perfect alibi for a murder: show the victim was alive and sending text message to you.....

Your poor friend is in trouble and trying desperately to get help from you.
With all the social interaction, how can this go wrong?

So, there you are, you've just permanently eliminated someone you didn't like/need.  But you need an alibi since the victim's real friends might finger you.

So, without leaving any finger prints, you grab the victim's cellphone and send yourself a quick message: "911 911 911 come to 5th and main...."
Poof, there it is on your cell phone.

You ditch the victim's phone in a dumpster, blocks away, as you skedaddle to a safe hidy-hole.
No Problemo!  Got away with it!

Except one problem: the police check the cell tower records to see who was "nearby"...
and, yep, the perpetrator was "nearby", and received a message from the victim.

... and the perpetrator doesn't have any witnesses as to just where, in that small wedge of reception, that he was.
Oops, instead of an alibi, it is almost a confession!

As reviewed in the article, several less than stellar individuals, seemed to have had the phone in their pockets as they sent the text message..... same cell tower for sender/recipient.
Not a good alibi unless you want to show that you were there!