<human>: Provide a brief overview of the text.

Bear with me on this one!

So, my friend Sarah met James one year ago. They started dating and he was pretty much living with her within a couple of months. They've had an up and down relationship, with many issues involving his ex. About six months ago, Sarah began receiving emails from 'Jumping Jack Flash', apparently proving that her BF was cheating etc. Basically, someone was trying to cause trouble.

Then the phone calls - it was actually her BF who was getting messages on his phone from an unknown male caller, telling him to 'get out of *location* or else'. Lots of threats, most of which were financial in nature.

Then they split for a while and the harassment stopped. They got back together. Today, she received a letter. The envelope was hand written, but the letter was typed. She said it reminded of someone's writing, then she pulled a sample of James's handwriting and one letter in particular (very distinctive) matched. 

Now, I'm not sure if the person who wrote this deliberately tried to copy James's writing, or if it's coincidence, or if it's James himself... (why he would do this, I have no idea!).

So, my question is... What next? Does anyone know if there's a way of comparing the writing? I have samples I'd be happy to PM to anyone with knowledge of this kind of thing. I'm very concerned for my friend. If it IS James, he's obviously nuts and she needs to get the hell away from him. 

ADDITIONAL INFO: She HAS gone to the police. She's waiting for them to visit her to discuss further.

I will update and will provide any further info as required. Thank you!
<bot>: Friend receiving harassing emails/calls/letters. What to do? Where can we go to compare handwriting to that of a suspect?