R v Kalekale: Science in the courtroom Paige McElhinney, forensic scientist, the forensic group emma priest, specialist criminal barrister, blackstone chambers

Why this case is interesting? Legal aid funded me 12 hours to work with a scientist, Paige McElhinney, to understand the evidence and prepare cross-examination. Paige McElhinney worked for ESR specialising in scene of crime and item examinations. She had broad oversight of items, choosing what would be sent for further testing, and assessing what the scientific results meant in the context of a case. What appeared initially to be VERY strong scientific evidence against Mr Kalekale was not necessarily the case and there was a lot of material for cross-examination; There were many items of clothing found in various locations, including shoes and weapons. There were lots of different aspects of science applied - Blood, Saliva, Trace as well as shoeprints and consideration of transference of DNA. We will discuss a few aspects of the case today to demonstrate what I learned in this trial. The ESR working casefile was 750 pages - a huge volume of material.

R v Kalekale - the allegations Mr Kalekale was charged for a series of aggravated robberies of petrol stations/ dairies in Auckland. 2-3 offenders, in disguises, carrying weapons, robbed commercial premises. The robbers would steal cigarettes and cash. Clothing was found in a rubbish bin in a park about 70 meters from the Kalekale address, in the house and in vehicles found dumped close to the robberies. The police suspected the Kalekale family, a known crime family. A known Kalekale address was very proximate to two of the petrol stations which had been robbed.

Man alleged to be Mr Kalekale Black Chuck Taylor Shoes - Black/ grey reversible jacket - white t-shirt (on head)

The Jacket: The briefing Minimal instructions – “ID the two offenders”

The Jacket: The science

The Jacket: The science Kalekale detected. End of examination.

DNA: The science Question: How many DNA sites are tested and how many sites do we have in our DNA? Standard DNA profiling = 21 DNA sites tested. Whole genome sequencing – does this add anything given the magnitude of likelihood ratios currently obtained? Question: What should we know about major/minor contributors to DNA when interpreting results? Volume of DNA from two or more contributors ≠ who touched last / longest Further interpretation required

DNA: The science Genetically based Consistent across body and different body fluids Consistent through time Wet and Dry stains Sensitive Recordable Discriminatory Blood Semen Saliva Nasal secretions Sweat Hair roots Skin cells

Standard examination protocol: Locate areas for DNA testing Collection of trace material (may link to scene(s) or suspect(s))

The jacket

The jacket

The jacket

Saliva testing Presumptive tests – used for biological fluid screening. Reacts with biological fluid and some other substances. Scientist relies on training and experience to determine if reaction is consistent with that of the biological fluid. Amylase is present at high levels in saliva. Presumptive test = Phadebas test. “Saliva probably present” or “probable saliva”. Amylase is water soluble and remains detectable until washed.

Trace/contact/ wearer DNA testing Biological fluids are a rich source of DNA. DNA may also be detectable from someone wearing or touching an item. Wearer – skin cells where garment contacts skin directly Wearer – can also target upper front of garment for saliva from speaking DNA results can also indicate who has been in contact with an item – care in interpretation. Collection = Minitape or swabbing

The jacket

The jacket

The jacket: In court More than 20 areas were tested on the jacket, 11 samples were taken from jacket. 1 sample sent from jacket for DNA testing from the front outside of the black side of the jacket only. This was a probable saliva stain on the outside of the jacket. This did not tell you who the wearer was. It was a mixed sample with Mr Kalekale as the minor contributor. What appeared to be a strong DNA “hit” for Mr Kalekale on the jacket was not necessarily that at all. Under cross-examination, the scientist had to conceed that they had not tested for wearer DNA and that Mr Kalekale’s DNA had come in contact with the jacket. As no probability ratio has been calculated (because it was not asked for) the scientist could not tell us how high the likelihood ratio was - it was only a weak link- more likely that not.

The jacket: where located?

Transference: Science Primary Transfer : Direct transfer from one surface to another Secondary Transfer : Transfer via an intermediary surface Applicable to all type of material including fibres, hairs, blood staining and DNA Needs an initial source of significant cellular material for subsequent transfer In order to conclude primary transfer, all other mechanisms of secondary (tertiary etc) transfer need to be excluded

The t-shirt Instructions – ID offender, locate DNA, distribution of material consistent with allegation (worn over face)

The t-shirt

The t-shirt

DNA101: What is the prosecutors fallacy? The scientists tell us: The probability of this result if 400,000,000 times more likely if this DNA came from Mr Kalekale than a random member of the public? What the jury hear: only one person in 400,000,000 has this DNA so it must be him. This is the prosecutors fallacy. Probability of A given B is not the same as Probability of B given A. If the accused was guilty, the probability of the evidence would be high. This does not then mean the probability of accused’s guilt is high.

Prosecutors fallacy in trial Confused? That’s the point. Effectively the statistic is a mathematical tool used by scientists to work out probabilities. XXN: What is the prosecutor’s fallacy? Your evidence is NOT that one person in 400,000,000 has this DNA is it? Excerpt from a closing: You heard about the prosecutor’s fallacy.- It means you need to take real care- it is not a case of 1 person in 400 million million having this DNA- make sure you understand the likelihood ratio when you consider this number. It is as scientific probability only. Don’t just jump to the conclusion that it must be Mr X’s DNA, that is not what it means at all.

The t-shirt

The t-shirt Standard Examination Areas for DNA analysis Presence of saliva (from being worn over face) Wearer DNA

The t-shirt

The t-shirt

The t-shirt

The t-shirt

The t-shirt in court Lots of areas where DNA indicated as present. Eight samples were taken from the t-shirt including wearer DNA, hair samples, blood and saliva. Only three samples were sent for DNA analysis. These were the saliva stain, wearer DNA from the collar and the blood stain. The ESR scientist accepted that the evidence told us that this t-shirt was likely to have been worn by Mr Kalekale at some point. The wearer DNA showed there were at least 3 contibutors and Mr Kalekale could not be excluded as a major contributor. The bloodstain linked to Male E. The DNA told us that it was Male E who had worn the t-shirt over his face as the large saliva stain has the majority contributor as Male E. No probability assessment had been made about Male E.

The Chuck Taylors: The facts The robber was seen to be wearing what appeared to be converse Chuck Taylor shoes in the robberies. A pair of Chuck Taylors were found at a well known Kalekale address. A shoeprint was found on a piece of plastic at one of the robberies. The Chuck Taylor shoes were sent into ESR for shoeprint analysis only.

Instructions – compare to shoe impression Instructions – compare to shoe impression. No instructions to ID wearer of shoes

The Chuck Taylors: The science Chuck Taylor footwear impression compared to footwear impressions located at scene: moderate to strong link between the show and the scene- but who wore the shoe?

Chuck Taylors: The science in court A. A DNA profile was obtained from the blood stain from the shoe and that DNA profile when compared to Mr Kalekale’s reference DNA profile indicated it could have originated from him, or the DNA on that sample so the two DNA profiles corresponded. Following that we were able to undertake a statistical evaluation of the DNA results in which I considered two propositions. Either the DNA present in that sample originated from Mr Kalekale, or the DNA originated from someone else selected at random from the general New Zealand population. Following statistical analysis it was determined that the likelihood of obtaining those DNA results is at least 20 million, million times more likely if the DNA in the sample originated from Mr Kalekale rather than from someone else selected at random from the general New Zealandpopulation. Q. Can that figure that you've just expression, at least 20 million, million times can that be expressed in words. A. Yes, we have a verbal equivalent scale. Any figure over one million is the upper limit of our scale and that provides extremely strong scientific support for the proposition that DNA recovered from the blood- stain from the inside of a right shoe originated from Mr Kalekale

Chuck Taylors: The science Instructions: Footwear impression comparison Blood staining noted and sampled

Chuck Taylors: The science

The Chuck Taylors: In court The ESR scientist agreed that he had recived the Chuck Taylors to compare shoeprints with the scene alone. He agreed that he had collected the blood sample incidental to his checking the shoes for shoeprints. He agreed that the blood found inside the shoe was likely to have been deposited from a single contact event and that this did not tell us who the shoes belonged to. He accepted the blood could have transferred when trying on the shoes. Because blood is a DNA rich source of DNA it would likely mask underlying trace DNA. He agreed that he did not check the shoes for wearer DNA (no minitapes used on inside of shoes or laces) so he could not tell us who the shoes were worn by.

Why the question matters Remember back to that rubbish bin found in the park near Haverstock Road. You will recall that in that bag were a number of items of clothing including the black t-shirt and the reversible jacket Remember what was tested for DNA? While 13 samples were taken from the jacket, only a sample from the outside front of the black side of the jacket was tested for DNA The black t-shirt was never tested

The same man? Image 1: Jacket black side out and white t-shirt Image 2: Black t- shirt and jacket grey side out.

Thank you Emma Priest Blackstone Chambers emma@emmapriest.co.nz Paige McElhinney The Forensic Group mcelhinney@theforensicgroup.co.nz 0800 88 88 26