Monday, November 30, 2020

DNA decontamination of fingerprint brushes

Must read

Chemotherapy causes patients to loose their fingerprints

A 65-year-old breast cancer patient in Mexico has lost her fingerprints, perhaps permanently. The woman was diagnosed with “hand-foot syndrome” caused by her chemotherapy...

Wallet-sized labs the next big thing

RMIT researchers are developing inexpensive, portable toxicology laboratories so small you could fit them in your wallet. Associate Professor Donald Wlodkowic, a bioengineering specialist, is...

You could be wearing your alibi right now

Your Fitbit could tell the truth, the whole truth and nothing but the truth. Personal data from wearable technology is now being used in...

Video: How to Compare Fingerprints

The following video provides a basic look into how fingerprint comparisons are performed and the level of detail in agreement that needs to be reached...
Michael Whyte
Crime Scene Officer and Fingerprint Expert with over 12 years experience in Crime Scene Investigation and Latent Print Analysis. The opinions or assertions contained on this site are the private views of the author and are not to be construed as those of any professional organisation or policing body.
- Forensic Podcast -

Genetic profiling of DNA, collected from fingerprints that have been exposed to various enhancement techniques, is routine in many forensic laboratories. As a result of direct contact with fingermark residues during treatment, there is concern around the DNA contamination risk of dusting fingermarks with fingerprint brushes. Previous studies have demonstrated the potential for cross-contamination between evidentiary items through various mechanisms, highlighting the risk of using the same fingerprint brush to powder multiple surfaces within and between crime-scenes.

In a 2017 Australian study published in Forensic Science International, researchers assessed the DNA contamination risk of reused fingerprint brushes.

Experiments were performed through the transfer of dried saliva and skin deposits from and to glass surfaces with new unused squirrel hair and fiberglass brushes. Additional new unused brushes and brushes previously used in casework were also tested for their ability to contaminate samples. In addition, the ability to eradicate DNA from used squirrel hair and fiberglass fingerprint brushes was assessed using a 1% sodium hypochlorite solution (bleach) and a 5% solution of a commercially available alternative, Virkon. DNA profiling results from surfaces contacted by treated and untreated brushes were compared to determine the effectiveness of the devised cleaning protocol. Brush durability was also assessed over multiple wash/rinse/dry cycles with both agents.

Varying amounts of DNA-containing material were collected and transferred by squirrel hair and fiberglass brushes, with detectability on the secondary surface dependent on the biological nature of the material being transferred.

The impact of DNA contamination from dirty fingerprint brushes was most apparent in simulations involving the transfer of dried saliva and brushes previously used in casework, while minimal transfer of touch DNA was observed. Alarmingly, large quantities of DNA were found to reside on new unused squirrel hair brushes, while no DNA was detected on new unused fiberglass brushes or brushes sold as DNA-free.

Following a very quick and simple method, squirrel hair brushes were easily and effectively cleaned with both hypochlorite and Virkon, with no evidence of DNA transfer between exhibits by treated brushes. Brushes were still deemed useable after multiple cleaning cycles with either agent. In contrast, fiberglass bristles became tangled and matted when wet and could not be cleaned effectively using either method. It is recommended they are disposed of following use.

Each laboratory should consider their current circumstances before adapting a cleaning method. The implementation of a program to monitor the effectiveness of the cleaning regime is also advised.

To learn more about the decontamination method and further results of the study,

Read the Paper Here

DNA decontamination of fingerprint brushes, Forensic Science International,

- Advertisement -

More articles

- Advertisement -

Latest article

Trees and shrubs might reveal the location of decomposing bodies

Plants could help investigators find dead bodies. Botanists believe the sudden flush of nutrients into the soil from decomposition may affect nearby foliage. If...

Are Detectives discounting the associative value of fingerprints that fall short of an identification in their investigations?

Every day, Fingerprint Experts in every latent office across the globe examine fingermarks that they determine to fall short of an identification....

Using the NCIC Bayesian Network to improve your AFIS searches

This National Crime Information Centre (NCIC) Bayesian network is based on the statistical data of general patterns of fingerprints on the hands...

DNA decontamination of fingerprint brushes

Using fingerprint brushes across multiple crime scenes yields a high risk of DNA cross-contamination. Thankfully an Australian study has discovered a quick and easy way to safely decontaminate fingerprint brushes to prevent this contamination risk and allows the brushes to be safely reused even after multiple cleaning cycles.

Detection of latent fingerprint hidden beneath adhesive tape by optical coherence tomography

Adhesive tape is a common item which can be encountered in criminal cases involving rape, murder, kidnapping and explosives. It is often the case...