Cell Tower Data – A Wisp of a Concept

A fundamental premise of the prosecutor’s case in the Pinyon Pines Murder trial was the pattern of connections to the various cell towers made by the defendants on the night the murders were committed.  The prosecution made much ado about their proximity to the entrance to Highway 74, the road that leads up the hill to where the crime occurred.

For a simplified version of the case they tried to make, imagine this:  Let’s say there is only one tower that serves the entire valley floor.  Let’s say it is located near the beginning of Highway 74, and that it can be reached at a few points along that road up the hill, but is blocked by various hills and dales along the road up.

Now imagine that you are driving around on the valley floor, making phone calls.  Does the fact that you are connected to that tower indicate that you are driving up the hill?

No, clearly it does not.

In the prosecutors scenario, there are three or four towers involved.  Robert Pape connects to the tower 707 near 111 and Date Palm, around 7:00.  At 7:01 he connects to the same tower again as he calls Sacred Heart Catholic Church, where he claimed he was going. (As it turned out, Mass had ended.)

His next call is to his friend Sam at 7:04.  This time he is connected to tower 705. This indicates that he is travelling south, toward Highway 111. The prosecutors say that this means they are driving towards the entrance to 74, but it also could indicate that they were travelling toward Sacred Heart Church before, and they are just still rolling in the same direction.

The next connections, at 7:05 and 7:06 are still connecting to tower 705.  To the prosecutor, this implies still travelling south toward 74.  It also just implies that they could be anywhere in that coverage area.  They could have turned east, from their southward trajectory, and are just driving somewhere near the tower.

It should be pointed out at this time that, after 12 years of delays and failures of the investigation, the cell tower ‘sector’ data has long since been erased.  Sector data allows a person to see not only which tower was connected, but on which side of the tower the call was made from.   Have you ever noticed that, on any given tower, there are three banks of emitters, each bank 120 degrees apart? The data is usually available as to which of those three banks you attached to.  This is critical. You could be north of the tower, but without sector data, they can say you are actually south east of the tower.  Or some such variant.

Remember that, in trial, it is the prosecution’s burden to put you at the crime scene.  It is not your burden to prove you were not there.  Nonetheless, with the sector data long gone, you are at a disadvantage when trying to convince the jury that the prosecutor is mistaken.  It is not supposed to be your job to do so.  The misleading and incomplete data should be disallowed.  But if the judge goes along with the prosecutor’s request, you’re screwed.  He did.  The defendants were screwed.  The jury can now be misled.

Back to our tower connections: The next contacts were at 7:09 and 7:10.  At this time they are connecting to tower 523, which is located on Country Club at Washington, right near the 10, in Palm Desert.  One would think that this implies that the defendants were east of where they were before. They were probably travelling east on their last connections to tower 705, and now they are closer to 523.  Makes sense.

But, if you really really want to believe the defendants are travelling up Highway 74, you can find a patch of coverage where tower 523 is visible from somewhere on 74.  The patch isn’t very large, but I suppose it could happen. But it’s a stretch. It all depends on what you want to believe.

There is a flaw here, though.  Remember the call at 7:06 that connected to tower 705? If they were travelling south to 74 and on their way up the hill, that call should have connected to another tower, Tower 745.  It is right next to Highway 74. They would have driven right past it!  But, instead, they connected to 705, as if they were travelling east.

Now, here comes the clincher!  The last connection made was at 7:13. Four minutes later.  This one did connect to tower 745, the tower next to Highway 74!  At this point, the prosecutors say that they must be a long ways up the hill.  But wait, there’s a problem!  Even though that tower is right at the base of the road up the hill, the vast majority of its coverage travels north.  Very little of it covers the 74 once the road starts winding.  To make that connection from 74, they would most likely still have to be at the base of the road.  But they already passed through the 523 coverage area, so, that’s not possible.  Only a teeny tiny coverage area appears further on up the road.

A More Likely Scenario

Take all those same tower connections and apply them to this speculated path.

7:00pm Frank Sinatra, heading east, approaching Monterey. – Tower 707 (Date Palm/111)
7:01pm Monterey, heading south, towards Sacred Heart Church – Tower 707
7:04pm Monterey, heading south still – Tower 705 (C.O.D. campus)
7:05pm Monterey, heading south still, Planning easterly turn onto Fred Waring – Tower 705
7:06pm Fred Waring, traveling east – Tower 705
7:09pm Fred Waring, traveling east, turning left on Cook – Tower 523 (Country Club and Washington)
7:10pm Cook St, traveling north, preparing to turn left on Country Club – Tower 523
7:13pm Country Club, near Cook. Connected to Tower 745!

Here’s where it gets interesting.  At this point, tower 705 is decidedly closer.  But wait! Something is in the way.  The elevation at CC and Cook is 250 ft above sea level.  The elevation for tower 705 is 190 ft. Sixty feet lower.  Add to that, the car was a street level. House level. Every building between the car and tower 705 was in the way!  Line of sight is pretty critical for cell towers. The expert witnesses testified to as much.

But wait, there’s more!

The elevation of tower 745 (next to the entrance of Highway 74) is over 500 ft!  A clear shot from Country Club and Cook.

So, the idea is simple: you can make all the same cell tower connections that these defendants made, simply by driving around on the valley floor.  It is a stretch to come up with a scenario that fits the prosecution’s case. But that doesn’t stop them. That’s their job!

The prosecution made a big deal out of this. Like several other items of evidence (shoes, footprints, DNA, spent cartridges, bank statements and the rest of the avalanche of meaningless evidence)  the idea is to mislead and baffle the jury into finding the defendants guilty.

It’s not about justice, it’s about winning!

In the twelve years since the horrendous murders occurred, cell towers, sectors and cell phones have changed dramatically. Therefore, making sense out of the data and testimony is impossible.  It is impossible to recreate the situation, therefore we are left with two or more possible scenarios; what the prosecution portrays,  the defense portrays, what we presented here, and potentially others.  But the burden of proof is on the prosecution.  It is not moral to convict two people on a possible scenario when other, equally possible scenarios exist.

*Rather than obtain cell town information from Verizon, the prosecution paid close to $20,000 to an outside company as their “expert witness”.

Comments 5

  1. Do we know if the sector information was lost, or if these towers were actually omnidirectional? As in they covered 360% radius from the position they were in, and didn’t have multiple sectors?

  2. “It is impossible to recreate the situation, therefore we are left with two or more possible scenarios; what the prosecution portrays, the defense portrays, what we presented here, and potentially others.”

    From what I’ve read both from the grand jury hearing transcript and from news coverage of the trial, both expert witnesses to the ping evidence (FBI Agent Kevin Boles & Gladiator Forensics specialist Greg Guillette) conceded that it is impossible to know with any real certainty now, whether Robert and Cristin drove up Highway 74, twelve years ago. You can’t know this from the ping data alone. As you state, too much has changed in the cell tower configuration in this time period.

    Verizon is in the process of moving on from CDMA and they have been working on this for some time-does this create a margin for error in analysis. Also, Verizon has removed many of their omnidirectional towers and replaced them with multiple sector antennas in recent years.

    And what I don’t think was ever established is if the radio frequencies of the towers being tested by Gladiator Forensics GAR device have been increased or decreased since 2006.

    Lower frequency radio waves travel farther distances, and are often used in rural areas where it is not as important that the transmission be strong, so much at that it can travel far; Higher frequency waves travel shorter distances, but have an easier time penetrating through solid objects.

    So, if there were fewer Verizon towers in 2006, and fewer subscribers to service then, it seems possible that the towers were operating at lower frequencies, which might mean that they would be able to reach greater distances than they do now-but physical obstacles might have been more of an issue as to reach.

    I don’t think this question was ever really answered.

    1. I have to make a correction. It isn’t radio waves at higher frequencies that penetrate matter more easily it is lower frequencies.

      Lower frequencies, say at 800/850 MHz travel farther distances, and can penetrate solid matter more easily (this is why radio station transmissions are at such low frequencies-this enables a radio show to access receptors in one’s home, penetrating through walls, etc.).

      Higher frequencies are less likely to travel as long a distance, and are more easily obstructed by matter-like a building, or lamp post, etc..

      CDMA or CDMA200, which is what was used by Verizon in 2006 (Verizon is slowly phasing out its use of CDMA), had only two frequencies at which it worked. 850 or 1900. You can see what the frequency differences are here between different cell phone companies. GSM vs CDMA. And CDMA as compared to LTE:


      The 1900 MHz channel utilized by Verison was often reserved for broadband use-internet access. The 850 MHz for voice-cell phone. But both frequencies could have been utilized by a cell phone.

      I don’t know what frequency the phones Cristin and Robert used in 2006 operated at. Could be they were able to access both frequencies. But has anyone checked this? Because 850 MHz would possibly travel farther than 1900 MHz, though both frequencies could still reach beyond a couple of miles. (Cell phones handsets have been known to ping towers as far as 40 miles, even farther, from their physical location).

      But Gladiator, for reasons I don’t understand, also tested LTE signals, that weren’t even in use by Verizon in 2006.

      Nothing I’m writing here is conclusive, but I point this out to show how much more complicated determining the range of radio waves from a given tower might be (than the explanations given at trial would indicate), especially if you are looking back in time twelve years.

      It does seem possible to me that the output (frequency being lower) of the towers in question here, was greater in 2006 than now. And that the handsets used by Robert and Cristin had greater output (worked at lower frequency) as well-this explaining how the two teens could have been in Cathedral City when they pinged tower 523, located near to Highway 10, and also near to Bermuda Dunes, Ca.—which was only 28 miles or so away.

  3. Pingback: A Tragedy compounded by a Wrongful Conviction | Pinyon Pines Murders

  4. When the cellphone expert testified in court, he said early on in his testimony that incoming calls are not reliable for accuracy. Then when the prosecution is having him show his maps in court of their locations, he uses an unanswered INCOMING call from Becky’s landline to Robert as proof the boys were on their way up the mountain. Seemingly forgetting about his own statement that incoming calls are not accurate for location accuracy. The defense did not seem to hone in on this point during cross and that was a big mistake because the jury walked away thinking the boys were actually on highway 74. (if anyone remembers this also came up with Adnon Syed and was one of the many factors that went toward his release)

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