nerosleuth told me about this case and I like December's posts here on WS so I'm definitely reading this. I'm still on page 3, so forgive me if I'm missing something.
First of all, I wanted to say I'm truly sorry for your (December's) loss and that of your family. I do hope you get some closure on this case eventually. This sounds like heinous crime and it should never happen, ever, much less to someone so young.
I've seen that you couldn't find some maps for Nashville from 1969. I tried to search since I often go on websites of historical maps. I haven't been able to find any 1969 maps but I'll keep looking on more sites and also try to find some from close years like 1970. The only map I've found is a topographical one, I can find it again if you like, but it doesn't show the streets and buildings in much detail, just main avenues and such.
However, I found this information here (it's .pdf file):
http://www.library.nashville.org/lo...ial_collections_division_finding_aid_maps.pdf .
It's from the Nashville Library. They have a special collection of historical maps and if you look at the list in that file, this includes a few 1969 ones including street maps. I'm not familiar with the geography of Nashville so I wouldn't know which areas they cover by looking at the names but you might be able to tell. If you can go to the library or ask someone who can you may be able to get a photocopy of the maps you need. They say in some cases photocopies may not be possible (I assume for conservation reasons) but in those cases they'll usually allow you to use a digital camera to snap a pic of the map.
If you can't go there in person, you can try to ask them via e-mail if it would be possible for them to scan in the map or at least take a picture of the relevant areas. You might want to mention you're Kathy's cousin and want a map for reference, though if that makes you uncomfortable you can just make something up.
I've brought this up in case you want to go there or at least get in touch with them. If you can't or don't feel comfortable e-mailing them, I don't mind doing it. Just let me know.
Here's the link of the page with the e-mail form and live help chat:
http://www.library.nashville.org/ask/ask_email.asp
I hope this helps! If not, I'm still going to keep reading and may be of more help once I'm done reading.