Stumbled over this during a research project for HIPAA compliance and text messaging (SMS is not HIPAA compliant in most cases, but I digress):
[URL=http://s1220.photobucket.com/user/kimi_SFC/media/threat_level_celldata-chart_zps89efb018.gif.html][/URL]
This image was released via a wired.com post that disclosed a secret LE memo regarding wireless carriers, and what is/isn't retained.
Here is a link to the PDF file to the U.S. DOJ memo:
http://www.wired.com/images_blogs/threatlevel/2011/09/retentionpolicy.pdf
I am still searching for the original wired.com post, but it is referenced here:
http://www.thebellforum.com/archive/index.php?t-59187.html
and here:
Secret memo reveals which telecoms store your data the longest
America's biggest wireless providers are holding on to sensitive data about
by David Kravets, wired.com Sept 28 2011, 9:10am PDT
(snip)
The single-page Department of Justice document, Retention Periods of Major Cellular Service Providers, (PDF) is a guide for law enforcement agencies looking to get informationlike customer IP addresses, call logs, text messages and web surfing habitsout of US telecom companies, including AT&T, Sprint, T-Mobile and Verizon.
(snip)
Verizon, for example, keeps a list of everyone youve exchanged text messages with for the past year, according to the document. But T-Mobile stores the same data up to five years. Its 18 months for Sprint, and seven years for AT&T.
That makes Verizon appear to have the most privacy-friendly policy. Except that Verizon is alone in retaining the actual contents of text messages. It allegedly stores the messages for five days, while T-Mobile, AT&T, and Sprint dont store them at all.
(snip)
The biggest difference in retention surrounds so-called cell-site data. That is information detailing a phones movement history via its connections to mobile phone towers while it's traveling.
(snip)
I dont think there there is anything on this list the government would concede requires a warrant, said Kevin Bankston, a staff attorney with the Electronic Frontier Foundation
More @ Link
http://arstechnica.com/tech-policy/2011/09/secret-memo-reveals-which-telecoms-store-your-data-the-longest/
This article references the original wired.com article - I will edit / post once I can find it. These are interesting points to consider, as LE undoubtedly has a lot to go on by just accessing Heather's phone records and analyzing them. Granted, if she was with Verizon, they would've had more (text messages).
I have no doubt they are actively using all cell phone data as an investigative tool to rule others in/out. All it takes is a phone number......