Medico-criminal forensic entomology has demonstrated its significance in strengthening criminal cases over the past three decades
South Africa’s most famous serial killer, Moses Sithole, and murderer Dumisani Mkhwanazi, found guilty in 1997 and 2020 respectively, are linked by something seemingly less remarkable — insects.
Medico-criminal forensic entomology has demonstrated its significance in strengthening criminal cases over the past three decades in a country where citizens are increasingly angered by police inefficiencies and shortages.
It was entomologist Mervyn Mansell who used forensic entomology to determine the sequence in which Sithole committed his murders in 1994 and 1995 in Atteridgeville, Boksburg and in Johannesburg’s suburb of Cleveland.
Although entomological evidence was used to build the investigation around the murders, it did not directly contribute to Sithole being convicted, because it was not used in court. This changed when Mansell became the first entomologist in South Africa to present entomological evidence in court that led to a successful murder conviction — that of Albert du Preez Myburgh in 2000.
Myburgh was found guilty of abduction, indecent assault and the murder of eight-year-old Cindy-Ann Bauer.
Mansell was able to determine the time of Cindy-Ann’s death using insects collected from her body weeks after she went missing. The time of death correlated with the time Myburgh admitted to have kidnapped the girl.
“The basic principle of forensic entomology is to provide an objective biological estimate of the time a victim has been deceased post-mortem interval [PMI] or the victim has been exposed to natural elements [such as] the local environment,” said Mansell, who is now retired.
He said he believes the most significant development is the South African Police Service’s victim identification unit getting a permanent forensic entomologist.
Aside from determining when a person has died, entomology is also able to show if a body has been moved by using the geographic distribution and behaviour of insect species, said entomologist Zanthé Kotzé, who is based at the zoology department at the University of Pretoria.
She said that in the 2004 Leigh Matthew murder case, a spider’s funnel-shaped web supported the state’s case that Donovan Moodley froze Matthews’ body for 12 days after murdering her. He then staged a murder scene next to the R82 highway near Walkerville, south of Johannesburg, where her body was found.
Insects can also determine whether there were any toxins such as drugs, poison or gunshot residue present in a victim because “the metabolites of these toxins may change the developmental patterns of the insects”, said Kotzé.
Lawrence Hill, who works at the department of forensic medicine and pathology at the University of the Witwatersrand, pointed out how valuable blood feeders — ticks, lice and fleas — are when found on a body.
“Sometimes you will find that DNA can be linked to a perpetrator or someone who was around the body just before death, because that DNA is still present if that insect was feeding on another person as well,” he said.
Even when no insects are found “it still tells us a little about the body”.
Hill was consulted during the police investigation into the murder of Palesa Madiba by Mkhwanazi. The University of Johannesburg student was killed in 2013 but her body was only found seven years later. When Hill was asked to determine the time of death, there were no insects on the body.
“What it did tell us [was that] the body was buried immediately as there was no colonisation of any insects on the body. Whatever happened, the death was concealed very quickly,” he said.
Despite the giant leaps forensic entomology – and entomological evidence – have made since the early 2000s, experts say that the failure to establish and fund the discipline, as well as the police not sharing information with entomologists, limits the contribution it can make in solving homicide cases.
For Hill, the use of forensic entomology must be more formalised so that police investigators can become more aware of its contributing qualities. “There are cases that might be relevant for investigations by [entomologists] but we never know about them,” he said.
Kotzé said: “Due to low numbers of expertly trained forensic entomologists, many crime scene investigators are not aware of the important information that insects can provide when found on a victim, and thus this evidence is often overlooked.”
She added that “very few” investigators and officers are trained in collecting entomological evidence.
“It often happens that evidence is incorrectly collected and handled at the crime scene itself. This includes omission of collecting live specimens, incorrect storage and preservation, and insufficient photography of the evidence in situ,” said Kotzé.
Allison Gilbert, an entomologist and head of the Human Decedent Identification Unit at Wits University, agrees with Kotzé’s claim of entomological evidence sometimes being overlooked.
She said that the police service is the only institution in the country mandated to handle evidence. And with limited personnel having to handle an overwhelming amount of evidence, it is only “diligent investigating officers and forensic pathologists who ask for ‘more’ to be done to assist in the death investigation”.
According to Kotzé, the main obstacle for forensic entomology – both in the police service and at tertiary level – is the shortfall of expertise, resulting in limited resources and funds to expand the field.
She added that training for police officers in basic collection techniques at crime scenes, “would go a long way in strengthening the use of forensic entomology in criminal cases”.
Aside from criminal investigations, insects can also contribute to identifying bodies. Hill, who assists in identifying people who have died of unnatural deaths, outlined how insect-parasites on a corpse can indicate that the deceased might have been in a certain area before his death.
According to the manager of the African Centre for Medicolegal Services, Stephen Franseca: “Insects are around us no matter where we are in the world. And so their impact on pathology and on the identification process is huge.” Franseca works closely with the Wits identification unit.
Although he uses forensic entomology the least of all of the forensic disciplines, he believes in the value of research and growth in each discipline because it allows different expertise to contribute to the investigation or the inquiry at hand.
And although forensic entomology has not yet been used to establish an unidentified person’s country of origin, this is possible, Franseca said.