Re: What is a Police Investigation
A confession is not admissible without corroborating evidence. That evidence can be circumstantial, but there must be something to back up the confession...other witnesses, physical evidence, confession includes details not publicly revealed, etc.
However, collecting recordings from surveillance cameras would only be done if it seemed likely that they would actually show something useful to the investigation. Most surveillance cameras record pretty low quality images. A gas station camera from across the street (even in the unlikely event that it was pointed in a direction to even see events across the street) would only show blurry silhouettes. The same for cameras on a nearby bridge. You could (probably) tell if someone was walking vs running or such, but you would not be able to identify anyone (probably not even tell male, female, race, or general age) or see if they were holding a gun. Motel cameras might well only cover the lobby/desk area. It's not like on TV where the detective gets an ATM camera from down the block and tells the tech to "enhance that area right there" and lo-and-behold they are able to read the bad guy's license plate from a reflection in a shiny hubcap of a parked car.
Behind the badge is a person. Behind the person is an ego. This is as it should be, person at the center and ego to the back.