Based on the assertion that you made, please explain how the police are able to complete their investigation without forensic data.
A police department is going to have an ongoing case load and investigations, at some point they have completed their investigation, they have gathered witness statements, they have gathered physical evidence, such evidence that is not witness statements id turned over to further agencies for analysis. And in this case the case was turned over to the SA's office.
Why would that be a surprise, this is not a cold case with no leads that is going to stay open.
My point about your assertion is that you keep saying that for some reason they needed to do more, they did what they felt they needed to do. they gathered evidence, they did not make an arrest, but they did turn the case over to the SA.
Where are you getting any idea that they should have done more, they did their part.
This is analogous to many other situations, a particular piece of an agency gathers information, at some point the scope of their gathering is finished and they turn it over to others.
Say I was someone who took crisis calls and did intake assessments and crisis screenings. In the case of intake appointments I did two things, I gathered information and made a summary of it, I then (with oversight by others) made recommendations and linkages. the appointment with the psychiatrist was often scheduled in the future at that point. Now I opened the client on my case load for the assessment and then transferred the client to the doctor or therapist. And that was it, my job was done. the client was closed from my case load.
Crisis assessments in the ED were similar, if they were not already an open client, I would meet with them, gather data and the best disposition would be determined. I would carry them on my case load until it was known what had happened to them, if they returned to the community or stayed in the community I had them on my case load for a brief period. But once that linkage was made for after care (or not if they chose that). They were closed off my case load, and often to the agency, the further gathering of information would be done by their doctors, therapists and other social workers.
And so in this analogy we have me as someone gathering information and making recommendations, there were times I would get them a 'crash appointment' with the psychiatrist and they would be transferred immoderately to the doctor's case load. There were other times they would stay on my case load for supportive counseling before transfer to a therapist or case manager. Or they would be transferred off my case load and to another while pending further appointments.
In all these situations the case was either transferred or closed. But either way it was closed from my role, there was often further information gathered by multiple individuals, inside and outside the agency I worked for, but the case was done for me.
Now the analogy here is that the SPD gathers evidence, they then make a multi-layered decision to arrest based upon that evidence. the case is then closed and transferred, while evidence is still being gathered.
In both situations there is a role, evidence is gathered and a disposition is made, further evidence continues to be gathered and analyzed. But not by the originating individual.
So where is your reasoning that the a police department would keep a case open after the evidence has been gathered? And especially since the case has been turned over to the SA?
You keep asserting that they should have kept the case open, where is this SOP and why would they do so?