Home > Future of Forensics > Small DNA Samples for Criminal Forensics

Small DNA Samples for Criminal Forensics

By: Ian Murnaghan BSc (hons), MSc - Updated: 15 Jan 2015 | comments*Discuss
 
Dna Crime Forensics Touch Dna Lcn Dna

Since discovering DNA, the technology and ability to analyse it has changed significantly. Many of the older challenges, such as efficiency and timeliness, have been virtually swept aside as better DNA analysis techniques have been developed over the years.

Smaller Sample Sizes From Skin Cells

Still, some sample sizes are so small and come from such a brief encounter or transfer that they can appear seemingly useless. That is, until recently when a technique was developed for obtaining and analysing these particular DNA samples.

Dubbed 'touch DNA', the technique represents the way in which police remove samples from only a mere few cells that remain after a person has touched something such as clothing. As humans, we shed enormous numbers of skin cells each day and these cells are transferred to clothing and other objects.

Touch DNA vs LCN DNA

One area of confusion is the difference between touch DNA and Low Copy Number (LCN) DNA. With LCN DNA, Forensic Scientists are able to analyse a very tiny sample of DNA, with anywhere from five to 20 cells.

However, a touch DNA sample will be analysed in much the same manner as a Sample From Blood or another common type of sample. It is also generally well recognised in a criminal investigation that goes to court proceedings. Commonly, PCR analysis is used to process a touch DNA sample.

Pinpointing a Suspect

So long as a form of contact occurs, there is virtually always an exchange of some kind. Assuming that during a crime, the person committing the crime transfers a reasonable amount of skin cells on some object at the scene of the crime – and if the item is identified and collected rapidly after the crime – then DNA analysis can yield information about the criminal.

Where is Touch DNA Located?

In theory, it's located virtually anywhere and everywhere. Our skin cells are transferred all of the time but in terms of what has already been accomplished, touch DNA has been used on samples from all sorts of objects ranging from a car's steering wheel to a person's clothing.

A challenge is that skin cells from a number of innocent people will still remain at the crime scene so the real test is for an investigator or forensics expert to decide where a sample is best collected.

Collecting Touch DNA

Touch DNA samples are extremely small and more challenging to obtain than other kinds of DNA samples for analysis. At the very basis of the technique is an investigator's ability to actually 'spot' where a suitable sample can best be found. A sampling approach needs to be used for obtaining the most cells possible to yield successful results.

A swab may be taken or even a piece of clothing cut off for collection of cells. Other collection methods include scraping and using tape to life off the cells.

Using Touch DNA

Touch DNA has been used in some well-publicised cases, such as the JonBenet Ramsey case in the United States. It's still not a widely used type of DNA collection for analysis but it certainly can be of significance in collecting skin cells and helping to pinpoint a perpetrator.

You might also like...
Topics
Latest Comments
  • Molls
    Re: The Rate of Decay in a Corpse
    Evening, just recently i have come home only to find lots of bluebottle/house-hold flies in my bedroom. I live in the attic part…
    18 January 2017
  • Whezzy
    Re: Rigor Mortis and Lividity
    My 28 yr old son died in his sleep. Cause of death accidental overdose. There are many things that make me wonder if that is an…
    15 January 2017
  • Zai
    Re: The Rate of Decay in a Corpse
    Hi! My father died two months ago. On the 13th of November.please I would like to know how his body has become?he was embalmed in…
    13 January 2017
  • Staypretty
    Re: Determining Cause of Death
    Confused & needing answers??? My father went in for a surgery a week before Christmas 2016 to have a spot of cancer taken off his…
    12 January 2017
  • Jessica
    Re: Drowning and Forensics
    Please help, my sister, went missing on January 31 2016, we knew right away something was wrong. She had been recently married but having…
    12 January 2017
  • B&B143
    Re: Determining Cause of Death
    My 8 yr old was hit & killed while getting on Upson County School Bus( the bus 20 min early, and the bus video magically disappeared,…
    12 January 2017
  • B&B143
    Re: Determining Cause of Death
    My 8 yr old was hit & killed while getting on Upson County School Bus( the bus 20 min early, and the bus video magically disappeared,…
    12 January 2017
  • tittyboi
    Re: Estimating The Time of Death
    Rectal thermometer? Sounds like abuse to the dead. 'am I right ?
    11 January 2017
  • Staypretty
    Re: Determining Cause of Death
    Confused & needing answers??? My father went in for a surgery a week before Christmas 2016 to have a spot of cancer taken off his…
    11 January 2017
  • gbexs
    Re: Forensic Archaeology
    I am a masters student of forensic science at the university of Ibadan, Nigeria. I am at the stage of writing my thesis and i want to write…
    9 January 2017
Further Reading...
Our Most Popular...
Add to my Yahoo!
Add to Google
Stumble this
Add to Twitter
Add To Facebook
RSS feed
You should seek independent professional advice before acting upon any information on the ExploreForensics website. Please read our Disclaimer.