Well it should be investigated when murders have occurred.
Steve,,my thoughts on the blood spots which were,just about noticed,on the passenger seat,could well have been from a woman at some time ( if you get my drift ) They were nothing to do with the murders and not worth bothering with.
To my mind,,everyone was struggling to find anything there was to be found,in which to secure Jeremys' arrest.
One thing to note,,that " everything " found,such as the silencer,file,were all " found " after the murders and not at the actual crime scene,which I would have said was iffy for a start.!