Be warned: this one is a very unpractical and unprobable one.
Imagine this:
Situation#1: I've just come to my office. Michelle is in but Steve is not. I'm looking for him so I ask Michelle: "Have you seen Steve?". Now that was pretty obvious.
It gets complicated:
Situation#2: I've just come to my office. Michelle is in and so is Steve. Steve takes a knife and stabs Michelle, then runs out of the office. I quickly check Michelle - she's OK, she will survive. I run out of the office too, deteremined to pursue and catch Steve. In the corridor, I run into Kelly, my colleague. Should I ask her "Did you see Steve?" or "Have you seen Steve?" My comments: I'm talking about definite past (a few moments ago/just now) and because Kelly has just seen me running and looking angry, she knows something is happening. I would use the past simple, especially if Kelly was upset and I got the impression she'd seen Steve escaping.
P.S. And no, we don't
usually stab one another at work.
