>Once a dt gets a suspect, they try to find evidence that
>supports that suspect, not try to find out if there is another
>alternative. If the evidence doesn't support, they'll move on
>to another suspect.

At least when it's a good detective. In many (I'd say most) cases, detectives/investigators have 2, 3, 4+ suspects being questioned and followed up on at one time, for various reasons. If you don't keep an open mind, you risk losing a suspect to flight risk or something else.