Macro, Meso, Micro: Core Concepts in the Development of Forensic Science
My presentation at the 2024 AAFS Conference
Macro: Body = Scene
In 529, Emperor Justinian approved the Codex Constitutionum, an extensive reconfiguration of old and new Roman law. In it, medical doctors were allowed by law to provide judgments based on their expertise, not just eyewitness testimony.
In the 17th and 18th centuries, “forensics” was body-centered and the purview of medical doctors only. Little else mattered and the remaining investigation involved shoe leather and knocking on doors. Murder was the morally important crime.
Micro: Things Unseen
The advent of toxicology shifted the perspective to things that could not be seen with the layperson’s eye, requiring interpretation to the layperson, who had to infer the truth.
The abstraction to the chemical level moved “forensic” work away from the body and into the laboratory:
The toxicologist’s expertise broached the barrier that medicine had claimed for so long. The doctor’s description could be countered by tissue analysis revealing things that could not be seen but could be proven, nevertheless.
The science still needed to be comprehended by the judge and jury, so the legal requirements continued to control science: It was not peer-to-peer.
Hans Gross’ 1883 textbook, Handbook for Examining Magistrates as a System of Criminalistics redefined what constituted evidence (more than just poison).
Gross’ early experience on the job with a wide variety of cases, from murders to arson to fraud, led him to realize that his formal education had not prepared him for the scope of crime and the breadth of expertise needed to investigate them properly. Gross pored over the natural, medical, physical, and social sciences, to re-educate himself. Gross wrote a manual in clear language that anyone with a basic education could understand.
He also coined the word kriminalistik (criminalistics) to describe the sciences as applied to criminal investigations, as opposed to criminology, the study of criminal behavior in society. This set forensic science apart. The book was immensely popular: When he died in 1915, the book had been published in seven editions and had been translated into a number of foreign languages.
Macro: Distinct analytical space with explicit rules
Gross recognized that it was the crime scene and not the body that was of paramount importance in a criminal investigation. This key aspect is often overlooked: Gross defined the crime scene as a distinct analytical space with explicit scientific rules of practice.
“The trace of a crime discovered and turned to good account, a correct sketch be it ever so simple, a microscopic slide, a deciphered correspondence, a photograph of a person or object, a tattooing, a restored piece of burnt paper, a careful survey, a thousand more material things are all examples of incorruptible, disinterested, and enduring testimony from which mistaken, inaccurate, and biased perceptions, as well as evil intention, perjury, and unlawful co-operation, are excluded…
Meso: Exchange and Relationships
Prior to Gross, unless the body held some obvious connection to the perpetrator, the investigator had no methods to connect the suspect to the scene or the victim.
Locard realized Gross’ vision for what evidence could mean: Interactions between people, places, and things during the commission of a crime created potential exchanges of materials. What was left behind was not the event but proxy data of the event, what we call evidence.
Anthropometry allowed for the identification of a person. But they had to be previously arrested and in the files (data base) and, importantly, currently present to re-measure for comparison to the files.
Fingerprinting changed this with Locard’s realization of Gross’ vision. They knew that perpetrator’s left fingermarks at scenes: For comparison, they only needed to have been previously arrested and fingerprinted. They did not need to be currently in custody.
This makes forensic science is a meso-level historical science. As a historical (reconstructive) science, forensic science has the ability to jump between times and spaces, scope and scale, giving it access to the range of activities from the macro through the mechanism of transfer (meso) to analyze the micro.
This provides the basis for possible source and activity interpretations.
Resources for the interested:
Burney, I. and Hamlin, C. eds., 2019. Global forensic cultures: making fact and justice in the modern era. Johns Hopkins University Press.
Burney, I. and Pemberton, N., 2016. Murder and the Making of English CSI. JHU Press.
Gross, H., 1907. Criminal investigation: A practical handbook for magistrates, police officers, and lawyers. Specialist Press, Limited.
Locard, E. (1957). Mémoires d’un criminologiste. Paris: Librairie Arthéme Fayard.
Research Forensic Library, Florida International University