I believe your time limitation of 'the past decade' is going to make your task difficult. There have been few changes in gun laws, for example, in Los Angeles in that period; it would likely be difficult to make a 'before and after' comparison.
Without going into the 'baggage'
John Lott has added, his research gives a good idea of the complexity of the effort, and the (lack of) persuasiveness of such data.