I think that was the same impetus as the WashPo dataset. I do wish the United States made it mandatory for agencies to submit their data to the FBI. I also wish Eric Holder's Justice Dept didn't withhold offender race data from the NCVS. Interestingly, the FBI's Unified Crime Report seems to cover about 50% of police-involved shootings, making it a pretty good sample (and the UCR is generally consistent with the NCVS which is a survey of victims). Leaving data collection up to the media is sketchy, notably because the media are more likely to report officer race if the suspect is black and even more so if the officer is white.

Obligatory: "Murdered" != Killed.