Ok, let's assume that the unknown driver went to the police and said "I drove xxxx there on Sunday night in my Toyota".
Don't you think the police would IMMEDIATELY have driven to the home or work of the person he named and taken them in for questioning?
Does anyone honestly believe the police would take a statement like that from the driver of the Toyota and then decided, "Nah, let's not go and see him yet, let's wait for some lab results"?
Remembering that the person they are trying to find has brutally murdered 3 people, would the police really just leave him to go about his business, visiting friends, going to work, watching TV with his family, for several days?
If they thoguth he had murdered 3 people they would be GROSSLY negligent if they didn't bring him in for questioning immediately. He would be considered extremely dangerous and they would have a first priority of removng him from the community so he couldn't kill anyone else.
<modsnip>. If they had a statement placing him at the house at the right time, of course they would have brought him in and held him while waiting for the lab results!