While criminal investigation does take time, yes, that doesn’t stop them from arresting people ahead of time if there’s even a moderate amount of evidence. I mean, that’s never stopped police from arresting “suspicious” black people (eg, someone who simply happened to be black in an area where a crime was allegedly committed by another black person; even if they look nothing alike). Police consistently treat themselves with kid gloves while treating people of colour as hyper dangerous and must be immediately arrested (or shot).