I don't know if this has been mentioned yet, but, my two cents:
LE didn't display the new website's map (the one with the interact-able red circles) at the PC. They could have. They had a satellite image map propped up there, all it was missing was the red circles. They gave the website, a .gov website, mind you -- not a .org website -- meaning the website has restricted access, and allows governmental agencies to monitor its traffic.
I suspect LE is watching the website's traffic very closely, in the hopes that the perp will visit it - to see the map. The map that you can only see by clicking on a website. LE can track the IP, address, etc. of the people who visit the site.
I think LE just set a brilliant trap.