Hi Chris,
Thanks, that was just the ticket. I used this shortcode syntax that worked fine:
[mashup query="post_type=crimes,units" width="98%" height="600" marker_link="true"]
(I also made a new custom post type “crimes” rather than leaving those as generic “posts.”)
The info at http://thereforei.am/2011/10/28/advanced-taxonomy-queries-with-pretty-urls/ was also very helpful.
Brad