Open Letter to Arie Zeelenberg

Mr Arie Zeelenberg, a fingerprint expert from The Netherlands, testified as a defence expert witness in the case. He delivered a lengthy PowerPoint presentation of about 208 slides. On this page, we will look beyond the visual façade of his report in order to examine the facts behind what Mr Zeelenberg elected to say, together with what he elected to not say . . . and why.

Here is Arie Zeelenberg’s full report in two parts:

Above: Slide 59 (Part 1) – Zeelenberg shows us that “the top and bottom lines are both curves

Mr Zeelenberg, not sure if you know this, but the fact is that when you take a lift from a conical drinking glass, then you will find two concentric circular arcs on the lift representing the top and bottom edges of the glass. The rim of the top edge would most probably cause a clear (curved) line but depending on the amount of powder on the bottom edge, it may vary in clarity. Being that as it may, if the two curves on Folien 1 were representative of a drinking glass, they needed to be concentric circular arcs and both would share the same origin (epicentre).

(A cylindrical glass will yield two parallel straight lines – but, both will be straight – not one curved and one straight.)

We would like to know from you in what way does drawing two straight lines under the top and bottom line features on Folien 1 prove that they are concentric and circular curves? Is that your idea of scientific investigation?

Would you mind doing the same on the image below.

Although there may be some irregular deflection above a baseline, are you sure it is a curve? Moreover, are you sure it is a circular curve? And then – are you sure it is concentric to the top line?

Fact is this, Mr Zeelenberg, and we can end the Folien 1 debate right here – if those curves are not concentric circular arcs – then a conical glass can be excluded. You were dead wrong.

It can be shown scientifically that they are not concentric circular arcs – therefore, no drinking glass.

And now for probably one of the most absurd, irrelevant and invalid experiments ever to enter the annals of forensic science.

About the curvature in the top line Director Botha (who conducted an investigation of Folien 1) said: “Base lines straight, top line curved. This is caused by rubbing foline over the rounded edge of DVD holder, more in the centre and less to the edges.” (Note – nowhere does Director Botha use the word “pressure”.)

What did Director Botha mean by this statement?

Whether Director Botha is correct or not is not the issue here. What is important is how Zeelenberg went about disproving (refuting) Director Botha’s rubbing theory. (Part 1, Slides 66 to 76)

Zeelenberg placed powder on two flat glass plates. He pasted a folien on each glass plate. On one glass plate, over the edge of the folien he placed a large metal ball, and on the other a heavy metal bar weighing more than 10 kg. After this experiment he removed the folien to show that the pressure applied to the folien, on top of a rigid glass plate, did not produce any curvature in the edge lines. He further claimed that such pressure would damage a DVD cover.

Mr Zeelenberg can you please explain how can a big ball and a big, heavy bar resting on folien on a hard, rigid glass plate tell us anything about Director Botha’s rubbing theory on a flexible DVD cover with a rounded edge?

Mr Zeelenberg concludes that “Very high pressure does not cause any curvature”. Then he quotes Director Botha – “curvature in top line caused by pressure”. Mr Zeelenberg could you please show us where in his report does Director Botha use the word “pressure”, when referring to the shape of the top line? – he used the word “rubbing”. Rubbing does not necessarily require significant pressure. Why did you misquote Director Botha?

Above: Slide 68 (Part 1) – Zeelenberg wanted to prove that pressure on the folien on the DVD cover could not have caused the curved top line on Folien 1. Instead of a DVD cover he used a flat glass plate. Can it get more ridiculous?

Readers can read more about this on the Bizarre Explanations page.

Mr Zeelenberg, you admitted in court that you are not a lip print expert and yet you still maintain to this day that the semi-elliptical mark was made by Fred’s bottom lip. What do you make of the fact that several real lip-print experts from across the world disagree with you? Is it acceptable Professional Conduct to testify in an area that falls outside of your area of expertise? Just like you did in relation to the dry drop marks, where you dabbled in fluid dynamics without actually having a clue what you were talking about.

Above: Slide 17 (Part 2) – Zeelenberg explains why lip prints will be sloped.

Slides 19 & 20 (Part 2)

Slide 21 (Part 2) – Zeelenberg makes this statement that lip prints will generally be sloped, like the one below. He, interestingly, says this is quite normal.

Mr Zeelenberg, would you mind telling us again why the lip print was incomplete and why lip prints would normally be sloped?

Could you also again explain your condensation theory, please? Are you sure that there was condensation in that area just under the rim? Can you also then explain why other prints were not influenced by it?

Above: Slide 58 (Part 2) – Zeelenberg said that the lip was put on condensation, this, according to him, obliterated the creases. It is curious that condensation does not go that high up, or much higher than the waterline. Even these images of glasses, which Mr Zeelenberg employed to support his own drinking glass theories, exhibit this phenomenon. His own images appear to undermine the theory that they are intended to prove. Perhaps if the glass was filled to the rim, his postulation might have been supported. But then one needs to consider the increased potential for spillage when an individual drinks in a manner that would produce a skewed lip mark (as hypothesised by Mr Zeelenberg). His images produced to support his glass theory do not help his argument. (It is further to be noted that there is no evidence of dried condensation, widespread damp or spillage recorded elsewhere on Folien 1.)

To prove his condensation theory, Mr Zeelenberg put a DVD cover in a fridge, and when it did not show condensation (and the lip had to be put on condensation according to him) he ruled out the DVD cover there and then. Mr Zeelenberg, would you care to tell us the logic behind this?

Read more about misleading experiments that ArieZeelenberg pulled here.

What do you make of the fact that Mariaan Booysens’s finger fits exactly on that mark?

Before you ask why a glove would be so wet and where the other prints are, we don’t know what was outside the recording scope of Folien 1 – this would be speculation. We only have Folien 1. What is best practice or not is irrelevant to the argument as to whether the mark was made by a lip or a latexed finger.

And yes, Mr Zeelenberg, it is quite easy to pick up and hold (or handle) a thin object like a DVD cover in the way Ms Booysens did to leave that mark.

You and Mr Wertheim have contradicted each other across a variety of issues which should be pivotal to proving your “lip print” theory. This is curious since you supposedly peer-reviewed his report. He said it was a wet lip on dry glass. You said dry lip on wet glass. He said the print is parallel to the rim, you said it is sloped – and should be sloped. He tied the lip to the prominent thumbprint to the right of the print (in positive view). You claimed a new thumbprint to put this new print more in line with the “lip print”.

While we’re on this.

Can you please tell us how you decided this is a thumb print? Does it match the thumb print of Fred van der Vyver?

Slide 10 (Part 2) (in negative view) – Zeelenberg claims a new thumbprint (bottom circle to the right).

And can you then tell us what you mean by “finding two thumb prints in this position is consistent with a drinking glass”?

Can you also please explain how this print was affected by wetness (condensation) but the thumb print directly adjacent to it wasn’t?

See our Report on the second thumb claim by Zeelenberg.

We would dearly like to know on what basis and by which method did you claim this specific print as thumb print. Expressing an opinion that is not based on good scientific principles and methods surely is not permitted?

Slide 71 (Part 1) – Zeelenberg aligns the Folien 1 print with the known print, demonstrating that no significant foreshortening took place.

Mr Zeelenberg, will a print on a round surface foreshorten or not? Mr Wertheim implied that it must be foreshortened (although it is not).

Who is correct here? You or Pat Wertheim?

If the print is not foreshortened – then what do you believe it would rather confirm: a print on a flat surface or a print on a round surface?

Slide 72 (Part 1) – Zeelenberg shows us that the known print’s sides are nice and straight and the Folien 1 print’s are not. Which can be expected. Moreover, he shows us that according to him a print on a drinking glass will rather tend to the triangular and that it will open up between first and second phalanxes. Please keep in mind the top rim of the glass is to the right as you view the image. He seems to be of the opinion that the finger will bend upwards (towards rim) and in a triangular shape rather than downwards in a drop-shape.

Can you just clarify this for us, please, Mr Zeelenberg. How do you think gravity and friction would have influenced the shape of the print? Are you absolutely sure that the print will be rather triangular?

Above: On various slides Mr Zeelenberg exhibited an overlay where he put Folien 1 on a DVD cover. Two problems: Swartz never said he put the folien in this landscape-on-landscape position* on the DVD cover, and Mr Zeelenberg produced his folien image disproportionately larger than the original. The pink outlines indicates what the image should have looked like if it had been properly scaled to the genuine size of the original Folien 1. Mr Zeelenberg’s casual treatment of the evidential images, and his disregard for the dangers of misleading the court as a result of his inaccurate creations, is highly irregular and unacceptable, irrespective of any noticeable influence on the result.

Can you please explain this, Mr Zeelenberg?

(*Swartz applied Folien 1 in a landscape position to the DVD cover, which itself was arranged in portrait position.)

Slide 27 (Part 2) – This, Mr Zeelenberg, is an utterly superficial statement. There are a variety of variables that influence the behaviour and appearance of drops on a surface, whether horizontal or vertical. Some of these include how the drops were deposited (impact speed, impact angles), contact angle, surface tension, temperature, humidity, contact line pinning, etc.

Slide 30 (Part 2) By this statement Mr Zeelenberg wants to suggest that surface tension is only “at play” on vertical surfaces. Care to give us proof of this, Mr Zeelenberg? Where did you read this?

Who peer reviewed your report, Mr Zeelenberg?

Mr Zeelenberg, why in 208 PowerPoint slides did you not once show us lip and index prints on the most appropriate three-dimensional medium, which is that of drinking glasses – instead you used only flat glass plates? The one image (Slide 24, Part 1) whereon you show an arrangement of two thumbprints and a lip print, shows your lip print as straight – not sloped. It really is rather curious that you chose not to illustrate your theory by displaying exemplar lip prints on drinking glasses, and instead employed only flat glass plates.

Some of Mr Zeelenberg’s own words on record:

“The ‘McKie case’ and related incidents can learn us a number of things; First of all that mind set can lead to contradicting and false conclusions both alleged identifications and misidentifications being proven wrong.

A greater concern is the fact that mindset can rob even experienced experts from the most basic abilities such as perception and rational. The ability to objectively re-examine material, to reconsider and if necessary reverse himself is a key quality for an expert.

The McKie case and its aftermath tell the seriousness of the problem and underline that more attention has to be paid to this competence. The inability to recognize a huge mistake on the doorstep is incompatible with a professional organization that wants to be transparent, accountable and reliable.”


“I have consistently broadcast one message: admit the mistake, apologise, learn from it, and move on.” [link]

“I firmly believe that an expert who acknowledges a mistake is a better expert from that day onwards. To be able to recognise fallibility is an important commodity in any expert. I know that because I have to tell myself daily that I am fallible. It is never too late to join the club.” [link]

“That future should whole-heartedly embrace transparency and accountability and should make room for a mature manner of handling differences. A culture that is open to the admission of mistakes is essential to that.” [link]

“The answer to your second question is yes. There is a mindset. It was shown last week that people worked back from a point of conviction. That has been seen and that is the trap that we all face.” [link]

Let’s see if Mr Zeelenberg demonstrates the integrity necessary to reverse himself” and join the club”.

If you are concerned about what you read here, then please send the IAI President an email, expressing your concerns in this regard and about Mr Zeelenberg’s ongoing membership of the IAI. Send your email to

Herewith the Reports of Professors Visser and Professor Chris Theron, both of who, independently, found that Folien 1 was not lifted from a conical drinking glass:

Open Letter to Roger Dixon

Open Letter to Pat Wertheim

Bizarre Explanations