Torch

[harryt]

Why in programs like CSI do they always look around with their torches why dont they just turn the lights on?

[WoWo]

Any number of reasons, specifically for CSI you could destroy finger prints on a light switch, order of the day is to preserve the crime scene and touching anything including a light switch would be doing that.

[BagPussAA]

Also, the torch beam will focus your attention on a more select area which will lead to you finding more evidence.