A bit of spy drama tonight

Let’s say, people of blogland, that a friend of yours has an email address.
Hypothetically.
Or, perhaps, a username on one of those chat boards stroke messaging places.
With, still purely hypothetically, a password reasonably, stupidly easy to figure out.
Let’s also say, still perfectly hypothetically, that this friend of yours, one day, realises that someone clearly has logged on as her.
Not once, not twice, but on a regular basis; and read her messages for at least the past two weeks.
That’s all purely hypothetical, of course.
Now, let’s say that this friend of yours, half freaked out, half high on an adrenaline rush, has four (hypothetical) suspects in mind.
All of whom are either/or 1) bored enough at work 2) curious enough by nature
3) possibly of a jealous disposition.

What do you think your purely hypothetical friend should do?

I’m going to slaughter the bastard.