I remember when cell phones first came out. They were analog devices instead of digital, and you could listen in on conversations with a police scanner if you knew how. Then with the advent of digital cell phones, that capability went away... for a while anyway. The Stingray technology mimics a cell phone tower, so can pull in everything a cell phone wants to send its way -- identity of phone, approximate location, text messages, conversations, etc.
Here is a link to some "guidance" put out by the Justice Departments for Stingray users within its purview. Note that there is nothing stated about what the policy was before this was issued just recently, long after Jessica's murder last December:
http://www.justice.gov/opa/file/767321/download
One telling item in the policy is on the second page:
"Moreover, cell-site simulators used by the Department must be configured as pen registers, and may not be used to collect the contents of any communication, in accordance with 18 U.S.C. § 3127(3)." [boldface added by me]
To me, this one statement is very telling. If such a device "...must be configured..." not to do something, the the logical presumption is that it can also be configured to -DO- that something that it must not. One wonders what the policy for Justice LE was -prior- to the issue of this official policy on September 3, 2015? Are there now cases out there with "tainted" evidence acquired by such non-complying Stingray configurations?
Let's hope Jessica's murder is not caught up in such intrigues. I would hate after everything that his been done to catch her murderer(s) to see them "walk" on such a technicality. I know the Supreme Court has already decided LE cannot attach a tracking device to a suspect's vehicle without a court order. With that in mind, it is not too difficult to figure out how the SCOTUS would decide the issue of using Stingray technology without a search warrant issued by a judge based on probable cause. When it comes to privacy of U.S. citizens, I don't think they care whether a tap is "wired" or "wireless".
JMO