Exploring the Use of Household Dust in Forensic Investigations

A recent study led by North Carolina State University revealed that it is feasible to extract forensic evidenceEvidence is any form of proof, such as objects, materials, or scientific findings, presented to establish or disprove a fact in a legal proceeding. It is used to reconstruct events and link or exclude individuals Read Full Definition from human DNADNA, or Deoxyribonucleic Acid, is the genetic material found in cells, composed of a double helix structure. It serves as the genetic blueprint for all living organisms. Read Full Definition found in household dust. By collecting samples of indoor dust from 13 households, the researchers were able to identify DNA from occupants in the house over 90% of the time, and DNA from non-occupants approximately 50% of the time. This research could potentially assist investigators in solving challenging cases by providing them with significant leads.

The researchers successfully extracted single nucleotide polymorphismsA single nucleotide polymorphism, or SNP (pronounced "snip"), is a variation at a single position in a DNA sequence among individuals. Read Full Definition (SNPs) from the dust samples, which are specific sites within the genome A genome is the complete set of an organism's genetic material, while genomics is the study of genomes, investigating their evolution, structure, and function. Read Full Definition that differ between individuals and correspond to traits such as eye color. This information can give investigators a glimpse into the identity, ancestry, and physical characteristics of persons linked to a crime scene. SNPs provide crucial forensic dataInformation in analog or digital form that can be transmitted or processed. Read Full Definition that can also be utilized by genealogy websites like Ancestry.com.

To conduct their research, Meiklejohn, corresponding author of the study, and her team selected 13 households of various backgrounds and gathered cheek swabs from each resident. Additionally, they collected dust samples from five different locations within each household, namely the top of the refrigerator, the bedroom closet, the top frame of the front door, a bookshelf, or photo frame in the living room, and a windowsill in the living room.

By using massively parallel sequencing (MPS), the research team was able to efficiently sequence numerous samples and focus on the single-nucleotide polymorphisms (SNPs) of interest. The findings indicate that DNA from around 93% of the known household residents in the study was identified in at least one sample of dust collected from each house. Furthermore, they detected DNA from non-occupants in over half of the samples obtained from every location.

According to Meiklejohn, this data could be utilized differently from traditional forensic DNA evidence. It might not be utilized to link an individual to a particular crime. However, it can be beneficial for providing clues related to the ancestry and physical traits of individuals at the scene. Additionally, it has the potential to provide leads to investigators in cases where little information is available. Although it is possible to differentiate between occupants and non-occupants, the duration for which an individual must stay in a household before leaving DNA traces remains unclear.

In the future, the researchers aim to investigate and determine the duration it takes for non-occupants to be identified in dust. Meiklejohn believes that their work has various practical applications and can prove useful in a multitude of investigative scenarios.

Reaserch: Using FastID to analyze complex SNP mixtures from indoor dustDOI: 10.1111/1556-4029.15246

Authors: Kelly Meiklejohn, Melissa Scheible, Laura Boggs, Robert Dunn, North Carolina State University; Darrell Ricke, Massachusetts Institute of Technology

PpPublished: Apr. 3, 2023 in the Journal of Forensic Sciences.

Household dust can be used as a potential source of trace evidenceTrace evidence - Physical evidence that results from the transfer of small quantities of materials (e.g., hair, textile fibers, paint chips, glass fragments, gunshot residue particles). Read Full Definition in forensic investigations.
Dust samples can contain sufficient DNA for analysis, making it a valuable tool for forensic scientists.
Household dust accumulates on undisturbed surfaces and is often overlooked by perpetrators, making it a useful source of evidence for investigators.
Massively parallel sequencing (MPS) technology allows for streamlined genotyping of dust samples, enabling the identification of individuals through DNA testing.
Genotyping single-nucleotide polymorphisms (SNPs) from indoor dust using MPS can provide valuable supplemental information to other forensic tools such as short tandem repeats (STRs).
Cheek swabs remain the gold standard for reference DNA samples, but household dust may provide a useful alternative in cases where direct reference samples are not available.
Research studies have demonstrated the potential of household dust as a forensic tool for crime scene analysis and domestic forensics.