Solving crimes with forensic science

Overview

LLNL researchers apply Lawrence Livermore’s forensic capabilities to help law enforcement agencies solve crimes. They use carbon-14 dating to help identify human remains and solve cases. They also assist in investigations of illegal trafficking of biobased material. Through isotopic analysis, they determine the age of biological material—data investigators use to verify illegal animal poaching or identify unknown human remains.

Scientists use the radiocarbon dating technique to analyze isotopic signatures in biological material and measure cellular and molecular turnover with high precision. They leverage the LLNL’s AMS capabilities to measure the ratio of carbon-14 to other carbon isotopes in a biological sample—including cells, tissue, and proteins—enabling scientists to determine a material’s age.

This radiocarbon dating technique, also known as bomb-pulse biology, takes advantage of the sharp increase and subsequent slow decrease of atmospheric carbon-14 concentrations that occurred due to atmospheric testing of nuclear weapons from 1955 to 1963. During that timeframe, the level of carbon-14 in the atmosphere doubled across the globe. Since above-ground testing was banned in 1963, atmospheric carbon-14 levels have been dropping due to diffusion, as carbon dioxide is incorporated into plants by photosynthesis and mixed with marine and terrestrial carbon reservoirs.

By eating plants, and animals that feed on plants, the concentration of carbon-14 in the human body closely parallels atmospheric concentrations. Thus, the rapid rise, sharp peak, and exponential decline of atmospheric carbon provides a molecular time stamp, enabling scientists to date biobased material more precisely.

Identifying missing persons and solving crimes

An investigator takes pictures at a crime scene. — LLNL researchers help law enforcement agencies solve crimes.

LLNL scientists use radiocarbon dating at CAMS to help law enforcement agencies identify human remains. By measuring the presence of carbon-14 in bones, teeth, or hair recovered by investigators, researchers can determine an approximate date of birth and death, and estimate the person’s age at the time of death. Investigators use this information to rule out potential victims and limit the possibilities to a smaller group of missing persons.

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Preventing illegal trafficking of biobased material

Graph showing the movement of radioactive isotopes in the Pacific Ocean. — LLNL researchers supported a criminal investigation involving illegal trafficking of ivory obtained from elephant tusks.

LLNL researchers assist in investigations of illegal trafficking of biobased material, using radiocarbon dating capabilities at CAMS. For example, they helped investigators who were prosecuting a case in 2013 regarding illegal trafficking of ivory. Prosecutors claimed that an ivory dealer in the West African country of Togo had violated the country’s ban on ivory trafficking, which was put in place in 1989. The defendant claimed that the ivory came from a stockpile that was older than the trade ban, and as such, the activity was legal.

Prosecutors asked LLNL scientists to conduct a forensic analysis of more than 1,500 pounds of elephant tusks confiscated from the defendant’s property. Through radiocarbon dating, the scientists determined that the samples included ivory from elephants killed after 1990, after the trade ban was implemented, and perhaps as recently as 2010, which contradicted defense claims and provided evidence needed to prosecute poachers. This type of evidence, which can lead to criminal convictions, also sends a deterrent message to poachers and traffickers.