Have heard nothing-zip-nada about any forensic investigation of the Las Vegas shooter.

I have found it strange that in all the discussions about motives about the shooter I have heard nothing about any drug testing or autopsies being performed. Nothing. It has been nearly a week and nothing has been reported or even said about this in anything of regular reporting. They all keep up the lack of motive thing. Why?

The closest I have seen is something (I think I read on CNN) about the Texas Tower shooter having a brain tumor that was putting pressure on his amygdala that may have contributed to the event and an oblique comment that the reporter wondered if the shooters brain was damaged with his "suicide". That's it.

Can anyone point me towards something that may explain this lack of focus on something so basic in forensic's ?