Chapter 35 — Exercises

Work these without looking back at the chapter first; then check yourself. Items marked † have full worked solutions in the answers appendix. There are no answers in this file. Mix of recall, applied reasoning, evidence interpretation, "spot the overstatement," ethics, and a cold-case extension.

A. Recall and definitions

  1. Define disaster victim identification (DVI) in one sentence, and state the oldest forensic question it exists to answer.

  2. Define a mass fatality. Why is it defined by the local system being overwhelmed rather than by a fixed number of dead? Give an example where ten deaths would and would not qualify.

  3. † Define commingled remains, and explain why "one set of remains equals one person" — an assumption a single-body case never has to question — fails in a high-energy disaster.

  4. Name the five Interpol DVI phases in order, and state in one phrase what each phase produces or does.

  5. Name the three primary identifiers and define antemortem/postmortem reconciliation.

  6. Distinguish a primary identifier from a secondary identifier, and give two examples of each.

  7. What is kinship matching in mass-fatality DNA work, and how does it differ from a direct DNA match?

  8. Define re-association of commingled remains, and name the one primary identifier uniquely able to perform it.

B. Applied reasoning

  1. † A disaster produces 300 dead in a county whose medical examiner's office processes about 1,200 cases a year working one body at a time. Explain, using §35.1, why the office cannot simply "work faster" and what kind of change the situation forces instead. Name two concrete features of a mass-fatality workflow that a single-body workflow lacks.

  2. A victim's intact body is recovered with undamaged fingertips, but the person is never identified by fingerprints. Give the most likely reason, and explain why "perfect fingertips" is not sufficient for a fingerprint identification.

  3. † In a fire disaster, fingerprints fail for most victims but dental identification succeeds for many. Explain the physical reason, drawing on Chapter 17, and state the disaster-specific ceiling on dental identification.

  4. A high-explosive event leaves mostly small fragments, few intact fingertips, and few recoverable jaws. Which primary identifier will carry most of the identifications, what indirect form will it usually take, and what does that form require investigators to collect from families?

  5. Explain why DVI runs all three primary identifiers in parallel rather than determining which is "best" and using only that one. Tie your answer to the idea that the identifiers have different failure modes.

  6. A team examining a body is told, before examination, "this is almost certainly the missing flight attendant, here are her details." Using §35.2, explain what is wrong with this, what feature of the Interpol framework it violates, and what should have happened instead.

  7. Explain the difference between depth and system in §35.1's "the system is the method." Why is heroic individual attention to each body the wrong instinct in a DVI?

C. Evidence interpretation

  1. † Re-read Figure 35.2 (the reconciliation matrix). Explain (a) why an exclusion empties a cell more confidently than a match fills one; (b) why a single match is weaker in a pool of 180 than in a two-person problem; and (c) what "convergence" means in the matrix and why it is the safeguard at scale.

  2. A reconciliation report reads: "PM-052 is identified as AM-031 (reported missing) on the basis of a direct STR DNA match with a random match probability on the order of one in many billions, corroborated by a concordant surgical implant recorded in the antemortem medical file." Identify three things this statement does well (where it is appropriately strong and honest).

  3. A second report reads: "PM-077 is identified as AM-044 because the body was wearing AM-044's distinctive jacket and wristwatch, which the family confirmed." Identify the methodological error, name the category of evidence being misused, and write the honest version of what this finding actually supports.

  4. In the reconciliation matrix, a victim's postmortem record is complete and high-quality, yet the victim remains unidentified. Give the structural reason this can happen, and explain why it falls unevenly across different populations of victims.

D. Spot the overstatement / junk-science alert

  1. † A press briefing states: "All 180 victims have been positively identified within 48 hours." Using the chapter, give two reasons to be cautious about a claim of complete, fast identification of a large disaster population, and describe what kind of cases would realistically still be open.

  2. An official says, "We confirmed his identity from his wedding ring — there's no doubt." Name the specific overstatement, the category of identifier involved, and the defensible role that the ring actually plays.

  3. A commentator argues that because a mass-grave anthropologist found gunshot trauma, "the forensic evidence proves the commander ordered the executions." Using §35.5 and Chapter 12, identify the leap and state precisely where the bone's voice stops.

  4. A lab reports a kinship-based identification as a flat certainty ("this is definitely her son") with no likelihood ratio stated. Explain, drawing on Chapter 9, why a kinship identification should be expressed with its statistical strength, and why a distant relationship gives a weaker result.

E. Ethics and reasoning

  1. † DVI is described as "conservative to the point of frustration," willing to leave a body unidentified rather than make a fast, uncertain call. Using §35.1 and §35.6, defend this conservatism as a duty to families, and explain why a misidentification is a "double catastrophe."

  2. In human-rights forensics, a family wants their relative's remains returned immediately while a tribunal needs the grave and remains preserved as evidence (§35.5). Lay out the tension honestly and discuss how a practitioner might weigh the humanitarian and judicial goals.

  3. The collection of a DNA reference swab from a grieving parent is called "simultaneously the most ordinary laboratory step and a profound human moment." Explain what doing this step well requires beyond technical competence, and why treating families as a distraction "misunderstands what the technical work is for."

  4. Victims who are undocumented migrants, unhoused, or from places with poor record-keeping are the most likely to remain unidentified (§35.4, §35.6). Is this a failure of the science or of something else? Explain what could reduce the inequity, and why it is an ethical concern a careful field must name.

F. Synthesis and validity spectrum

  1. † Place these under disaster conditions on the validity spectrum, justifying each: a direct single-source STR DNA match; a dental identification with good antemortem radiographs; a fingerprint comparison by a confident examiner; an identification based on a tattoo alone. (Strong → weak/improper.)

  2. Explain how the autopsy's "no soot in the airways" finding (Chapter 11) and this chapter's discipline of independent postmortem examination (§35.2) both express the same underlying principle: describe the evidence on its own terms before fitting it to a theory.

  3. In one paragraph, explain how this chapter advances at least two of the book's four themes (exclusion over proof; the validity spectrum; cognitive bias; the CSI effect cutting both ways). Name which themes and how.

G. Cold-case extension

  1. † Cold Case. The Chapter 35 Case File is an aside, not new evidence. In your own words, write the note you would add to your Appendix I workbook comparing the single-victim identification of Marcus Diallo (Chapter 17) with mass-fatality reconciliation. State (a) three simplifications that made the Diallo identification easy; (b) why the prosecutor's-fallacy worry of §35.4 did not arise in his case; and (c) the honest statement of what this aside adds to the case (it adds no new facts).

  2. Cold Case, integrative. Suppose — counterfactually — that the Mill Creek fire had killed several people whose remains were commingled and burned. List three ways the identification problem would have changed from the single-victim case, and name which primary identifier would likely have become most important and why.

  3. Cold Case, honesty check. A junior investigator proposes "confirming" Diallo's identity from the wallet and truck found at the scene, to save the cost of dental comparison. Using the primary/secondary-identifier distinction (§35.3), explain why this would be a methodological error even though the wallet "obviously" points to Diallo — and what the wallet can legitimately contribute.

H. Short writing

  1. In 150–200 words, explain to a juror (or a journalist) why identifying the dead after a major disaster takes weeks or months and costs a great deal — and why the slowness is a feature of doing it correctly, not a failure.

  2. † In 150–200 words, contrast the humanitarian and judicial purposes of mass-fatality and mass-grave forensics. What does the identification of the dead give a family that nothing else can, and what is the science honest about being unable to deliver?