Gun selection in TV shows

[zackmann08]

So I'm wondering if anyone can shed some light on the following... In an Episode of CSI: NY a TDI Vector makes an appearance as the weapon of choice by a bank robber. What would inspire the selection of this weapon? I would have expected to see a MAC-10 or an Uzi or even an MP5. Is this a decision that is made by the director/writers or by the armorer? I'm curious why an uncommon gun would make an appearance in this way. Obviously if you are arming an NYPD detective, you are going to use a Glock because that is based on what they actually use in real life. How does the decision for thugs and criminals go? Any one have any insight??

-Z