In a court of law, the evidence of an expert witness may be countered by that of another expert, and better still, a more qualified and experienced expert and prudent defence lawyers use this technique frequently.
And so the defence team in the trial of the accused persons in the Kiruhura murders invited a 47-year-old holder of a Master’s degree in geology to counter the prosecution evidence in respect of a soil analysis carried out at the Government Analytical Laboratories in Wandegeya. This expert had 20 years experience in geology and his work involved analysing soils and minerals.
Disclosure of evidence
In a criminal trial the prosecution must declare the evidence in its possession to the defence at the completion of investigations and the start of the trial. This is to avoid what lawyers’ term “trial by ambush”. A report compiled by the expert from the Government Analytical Laboratories in respect of the analysis of the soil samples was part of the evidence that the prosecution shared with the defence lawyers who subsequently consulted with the independent soil scientist.
The independent scientist told court he knew the author of the report quite well and to him the author was, in truth, a food scientist and nothing more than that. Under cross-examination he was to tell court that food scientists do not carry out soil analysis.
The author of the report used the wrong units in quantifying the different components of soil and some of the results were incompatible with soil science. For example what the report called “mineral profile” should have been “profile of the elements of the soil”.
And to the expert, to accurately determine some of the parameters in the report, the minimum amount of soil sample needed would have been 30 grams and not the very minute amounts of samples that were provided in this case. The report did not mention the particulars of the methods used in determining the parameters reported. Usually some of the parameters should have been given in a particular range but in the report some of the parameters were given in specific figures an act that was odd, strange and unprofessional.
The report of the Government analyst shocked the independent expert as it was a very unprofessionally made report. In his own words he told court that if the report had not been signed, he would have thought that the results were plucked from elsewhere and simply inserted in this report where they did not belong. To him this report was hurriedly made and by an officer who was certainly not in the right frame or state of mind.
The prosecution lawyers attempted to discredit the evidence of the soil scientist by insinuating that he was not a forensic scientist, and indeed he accepted that he has never been trained as a forensic scientist. Unknowingly though, the expert was giving technical expert in a court of law, and this alone made him a forensic scientist, whatever the term forensic scientist means.
The expert explained the technicalities of analysing soil samples and the correct units that should have been used and mentioned the machine used to analyse the samples, the Atomic Absorption Spectrophotometer (ASS) machine. The government analyst had earlier told court that he had a certificate in using this machine.
The witness further explained to court the difference between an element and a mineral and how the acidity or alkalinity of soil is determined and he stated in no uncertain terms that the minimum soil sample to carry out this test is 30 mg.
And to him the procedure of soil analysis must be the same, whether the results are to be used in forensic or geological analysis. In forensic cases minute amounts of samples may be the only samples obtained but the onus is on the analyst to state the method used to arrive at the results, which was not reported in this particular case.
The expert insisted that the results presented to court were defective although he did have an alternative result for the simple reason that he had no opportunity to carry out an independent analysis of the samples.
The prosecution lawyers attempted to impute bias to the expert’s evidence; the expert had received no written instructions, but verbal instructions to critique a report and point out irregularities in it. But to the expert he did not study the report with the initial impression that it had irregularities.
This was his first time ever to be called to court to review a report made by another expert. He, however, did not make a formal report of his observations and opinions that the court could have independently verified.
There is no doubt that the forensic, or more correctly, the physical evidence, in this case;
• Did not place any of the accused at the scene of crime
• Did not identify any murder weapon
• Was misinterpreted in some instances
• Was out rightly fabricated at least once
• Was totally unreliable and unequivocally challenged
Next; The unanswered questions
To be continued