The cell phone digital forensics is complicated but needs to be understood in this thread, because I think it is key to understanding events leading up to the disappearance. In the trial, there was contention between the testimony of Ms. Rexing (prosecution, Day 2) and Mr. Williams (defense, Day 6) regarding the last several data sessions in the call detail record (CDR) for Karen’s iPhone. I welcome comments and criticisms here.
I watched those expert witnesses a few times, and here is what I gather about a CDR. First of all, a CDR log describes all the data/text/calls that were performed using Verizon networks that would be billed. To clarify a bit, a CDR does NOT record random “pings” as a phone moves around in an unused state. If something is in the CDR, then the phone is doing something to consume Verizon network data occupancy. Could be a regular phone call, SMS message, iMessage, email refresh, YouTube video, Skype call, weather app refresh, etc. The content of those things are not necessarily logged in the CDR. Verizon itself may not even know the content of the data, for example iMessage is encrypted by Apple through the network so Verizon has no idea. In addition, when a CDR is empty for a while, that does not necessarily mean that the phone is off or destroyed. It merely means that the device is not using Verizon network occupancy. iPhones have apps that are constantly using data even without the user doing anything, so they are unlikely to have long periods of no data activity. It is also possible that the device went on WiFi, not using Verizon network occupancy.
The tricky aspect of this case is that cell service in the area of the Swift home was TERRIBLE in 2011, so the Swifts had a network extender. A 3G network extender in 2011 might be something like this,
3G Network Extenders: Your Top Questions Answered. This thing clearly vexed Dyer County LE since the beginning.
Ms. Rexing's testimony focused mostly on the time-in-advance data, which essentially infers range from a tower to deduce possible phone locations. From this, Ms. Rexing could show Karen’s movement through billed data sessions in the CDR:
1:28am - appears to be at Bona’s house, confirming testimony
1:37-1:45am - on way to Roellen to get Ashley
1:52-1:53am - on way to Swift home
2:08-4:37am- network extender activity
4:57am- data session with no ranging or sector data
5:00am- data session with no ranging or sector data
5:04am- data session with ranging to cell tower near Mississippi River, location could be any of the areas of interest.
5:09am- data session with no ranging or sector data.
(It is not actually revealed or verified what she is doing on the phone at any point of this or who she might be communicating with, I assume that the prosecution/defense truly doesn’t know, or it is unimportant)
The defense used this to theorize that Karen Swift’s iPhone left the Swift home at 4:37am, never to return. But, Ms. Rexing never explained why ranging data was missing on the last few.
Mr. Williams explained that the final data sessions that did not indicate ranging or sector data were actually using the network extender at the Swift home. He showed this using the “home agent ip address” of the data session, which was the Swift network extender for all of them. So, the last time Karen’s iPhone was connected to the Swift home was 5:09 am, which was also the last known activity of Karen’s iPhone. The phone was never in the Mississippi River area, as was often reported early in the disappearance. That was a misunderstanding of the data and was honestly a huge waste of search resources at the time that mattered most to the investigation. It was apparent that the prosecution/LE did not understand what a “home agent ip address” was, or for some reason decided it wasn't important.
But that was not actually the final electronic activity of Karen’s phones…..
According to testimony of Joel Wade (Day 5, defense computer expert witness), there was a call to voicemail at 9:57am on Karen’s second phone, the Voyager phone that the Bona’s gave her, on the day of the disappearance. Joel surmised that it could be on the Swift network extender or on WiFi, but had no proof. Furthermore, I am 99% sure that the Voyager phone back then didn't have a WiFi feature. No one asked Joel about the “home agent ip address” of that call, and on Day 6 when the concept of home agent ip address was revealed to the prosecution, assistant DA Box never asked Mr. Williams about the Voyager phone call to voicemail. If the home agent ip address can be obtained for that final call to voicemail on the Voyager phone, then that information either fully excludes David (i.e., not the swift network extender) or, in my opinion, is proof of his guilt (i.e., is the Swift network extender).
I hope that the prosecution/LE has discovered something about the final call to voicemail as they await the possible manslaughter trial.
www.localmemphis.com
