Open letter to Roger Dixon

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This is an open letter to Mr Roger Dixon. In the past we have already tried a couple of times to engage with him on the issues we will raise in this letter. Both times he did not respond. We will post Mr Dixon’s verbatim response, if any, on this page when we receive it.


The State’s response to the Wertheim report was to ask Senior Superintendent Roger Dixon, a Control Forensic Analyst at the Scientific Analysis Unit of the Forensic Science Laboratory in Pretoria to examine Folien 1 in order to determine whether it was lifted from the DVD cover or from a drinking glass.

On 5 December 2006, Roger Dixon visited the office of the Paarl LCRC in order to conduct various tests on DVD covers and drinking glasses “collected from Inge’s flat” at 21 Shiraz. Dixon was assisted by Captain Danie van der Westhuizen who did the powdering and lifting. Then through a process that “required skills in image analysis and comparison” he compared the lifts with Folien 1 and came to the ultimate conclusion that in his opinion Folien 1 was not lifted from a DVD cover but instead from “one of four glasses found in Inge’s flat”.

Dixon’s conclusion verbatim:

In my opinion the back folien described in paragraph was not ‘lifted from a DVD’ but instead from one of the four glasses described in paragraph 6.4. The features observed on the folien match test lifts made from the glasses, and not those made from the DVD covers.

The black folien Dixon referred to was Folien 1 and the four glasses were those numbered 1, 6, 7 and 8. Please see the photo of the four glasses below.


Dixon reported his results in a signed affidavit, dated 12 December 2006, in terms of Section 212 of the Criminal Procedure Act 1977 (Act 51 of 1977).

This affidavit compelled the Director of Public Prosecutions to, on 13 December 2006, send a letter to the Advocate Dup de Bruyn, Fred’s lawyer, which said: I hereby confirm that the State no longer intends to proceed with evidence concerning your client’s alleged finger print on the DVD holder.

This affidavit was accepted as prima facie evidence by the court. Roger Dixon did not have to testify in court.

Judging from Judge Deon van Zyl’s verdict below Dixon’s affidavit was crucial to the outcome of the case. It dealt the legitimacy of Folien 1 a severe blow.

[140] It follows that the state in no way submitted sufficient evidence to affect the prima facie case, as contained in Senior Supt Dixon’s affidavit in the least. This prima facie case was indeed strengthened considerably by the highly expert presentations of Mr Wertheim and Mr Zeelenberg.

[141] In their comprehensive reports and impressive testimonies, did they affirm and expanded on Senior Superintendent Dixon’s findings in his affidavit point by point.[…] They were both of the opinion that its (Folien 1) came from a comical drinking glass about 80 mm high. …

We have some questions for Mr Dixon which we hope he can answer:

  • Where did the 11 glasses come from? You said that they were collected from 21 Shiraz. Do you have the chain of custody documentation to prove this? Your affidavit fails to provide the evidence numbers for each glass and makes no reference to any chain of custody documentation like you did for Folien 1.

Even Pat Wertheim had this to say during his court testimony: M’Lord, I was advised that the drinking glasses in Inge Lotz’ flat, many of them had been retrieved by her family, rather than collecting five at the scene, the police had recovered them from her family at a later date. Again there’s no continuity, there’s no chain of custody, there’s no provenance to a drinking glass received from the Lotz family that might have come from Inge’s flat.

Mr Dixon, in formulating your response, please consider the following facts:

  • You did your experiments 1 year and 9 months after the death of Inge Lotz and therefore you cannot expect us to believe that after all this time the police were in possession of 11 drinking glasses when they couldn’t even hang onto a DVD cover for longer than two weeks.
  • Some time after Inge’s death Mrs Juanita Lotz, her mother, with the assistance of a friend cleared away all of Inge’s belongings in the flat and took them to her home in Welgemoed, drinking glasses included.
  • In December 2005 Mrs Lotz received a visit at her home in Welgemoed from Director Attie Trollip and Director Ruben Botha who wanted to inspect Inge’s drinking glasses which at the time were still packed away in boxes.
  • Although Mrs Lotz’ memory was somewhat vague during her court testimony there is no recollection whatsoever that Trollip and Botha collected all Inge’s glasses (i.e 11 of them) but rather only two glasses – one prototype of each type of glass that Inge had.

How could you make such a definitive and far reaching statement that Folien 1 came from one of four glasses in Inge’s flat based on glasses with no evidentiary value? Maybe someone supplied you with the glasses – but the responsibility was still yours to ensure that they were accompanied by proper chain of custody documentation.

  • Why did you claim in your affidavit, under oath, that the distance between the two lines on Folien 1 is the same as the height of four of the glasses (belong to a set) when there is a clear 3 mm difference? Is this why you didn’t state in the dimensions of each of the 11 drinking glasses in your affidavit?
  • The distance between the lines on Folien 1 is about 80 mm. Zeelenberg and Bekker even suggest sub-80.
  • The height of the glasses which you claimed under oath Folien 1 was lifted from is 83 mm, and this is clearly evident from your photo of one of the four glasses (below).


On Folien 1 a difference of 3 mm is very significant – it exceeds any reasonable margin of error.

  • In Par 7.5 of your sworn affidavit you stated:

The concentration of powder on the lower line is not consistent with the line having been produced as a result of a first lift from the middle of the DVD cover, representing the edge of the previous folien, but rather consistent with an edge having been powered.

How could you come to this conclusion if from Par 6.1 it is evident that you did not experiment with ‘double lifting’.

Lifts were made of DVD cover 31 as described in paragraph 3.1.1 on the top half of the front of the cover …

Nowhere in your affidavit do you mention that you experimented with double lifting – on what scientific basis did you come to your conclusion?

  • In par 7.3 of your sworn affidavit you stated:

The positions of the fingers and the right thumb as seen on Folien 1, is consistent with the lift having been taken from one of four glasses described in par 6.4. In addition, the lip mark produced while drinking from glass 8 is in the same position as that observed on Folien 1, above the left fingers.

Why did you not describe the drinking action you used to produce your glass #8 lift? Was your drinking action based on normal drinking considerations? If you used the normal drinking action as previously described by Mr Wertheim: lift the glass with left hand – pour in water with right hand – put glass down – pick up with right hand and drink – it is impossible to get the lip print above the left fingers – and impossible to get the finger and thumb print in the same relative position as on Folien 1.

  • As a scientist you should have known that the edges of a round conical drinking drink glass will leave concentric arcs on a lift. In fact it is a simple task to calculate the radii of the curves from the glass’ dimensions. Then it should have been a simple task to overlay these calculated curves on Folien 1 to confirm a good fit before making a conclusive statement like: … (Folien 1) was not ‘lifted from a DVD’ but instead from one of the four glasses described in paragraph 6.4. You didn’t do this, did you? Why not?

By your conclusions you seem to support the notion that the ‘bottom line’ on Folien 1 is a perfectly circular curve.

We have taken the liberty to use the dimensions of the glass that you claimed Folien 1 was lifted from – we calculated the radii of the top and bottom lines and we overlaid it to scale on Folien 1. Please see below.


The top white line of Folien 1 is used as anchor. By way of simple geometry we calculated the top and bottom radii accurately by using the top and bottom diameters and the height of the glass you implicated (67/63/83) – and with this concentric unit (circles with same epicentre) did an on-scale overlay on Folien 1 in order to see if the implicated glass could have made those lines on Folien 1. The tangent line (’12 o’clock line’) of the two established concentric circles that represent the curves your glass would have left, was put in line with the middle point (12 o’clock point) of the Folien 1 top line after this top white line was brought as horizontally as possible. This ensures that the curves are most prudently placed on the folien.

Below is a cleaner and slightly bigger image for better viewing.


Do you still maintain that the lines of Folien 1 are both perfectly concentric and circular curves? And even more importantly, do you still maintain that any of the glasses that you experimented with could have made these lines? And even more importantly – when you compared your experimental lifts with Folien 1 these differences should have been blatantly obvious even to someone that is not an expert in ‘image analysis and comparison’ – and yet you did not document it in your affidavit. Why did you decide not to disclose these crucial and significant differences?

(We grant that it seems like the top lines are a perfect fit. However, as we have established with regression analysis, the Folien 1 top line is not a perfect circular curve. The coloured line obscures the straight alignment of the line to the left as you view the folien. What is rather significant, is that there is no fit on the bottom line. Not even close. Not with respect to curvature or position. The coloured curves need to fit as a concentric unit on the Folien 1 lines, they do not.)


  • You stated in Par 7.4 of your report: The water droplets observed on folien 1 are consistent with water droplets having dried on a vertical surface. They are oval shaped with their longitudinal axis parallel to the bottom of a glass.

Are you saying that oval shaped drops are only found on vertical surfaces? Can you refer us to a single academic or research resource to confirm your opinion that oval shaped drops with concentric ‘white rims’ or contact line deposits (like those on Folien 1) cannot possibly form on a horizontal surface? You had access to the original Folien – did you not observe the multitude of other water drop marks with all kinds of shapes and sizes and some of whose longitudinal axis are not parallel to the ‘bottom of a glass’?

Is it a coincidence that Mr Arie Zeelenberg latched onto the same flawed idea that oval shaped drops are synonymous only with vertical surfaces and not horizontal surfaces?

What happened here – and why?

Open letter to Arie Zeelenberg

Open letter to Pat Wertheim

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