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Forensic Science Regulator Report

Questions to the Mayor of London – answered on 19th March 2020.

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Photo of Caroline Pidgeon Caroline Pidgeon Liberal Democrat

The Forensic Science Regulator’s report of 25 February stated that, nationally, over 1,100 DNA profiles on the National DNA Database have been contaminated by police officers and staff and are having to be removed. How are you working with the Met to ensure that contamination of evidence in the Met is minimised?

Photo of Sadiq Khan Sadiq Khan Mayor of London

I am aware that recent advances in DNA technology have resulted in an increase of sensitivity. Considering this, the Metropolitan Police Service has reviewed all procedures, in particular the anti-contamination procedures to comply with best practice.  It is accepted that even with the use of best practice anti-contamination procedures DNA contamination cannot be entirely eliminated.

DNA elimination profiles for MPS police staff and officers that come into direct contact with forensic exhibits are loaded onto relevant elimination databases.  All DNA profiles generated from MPS crime scene exhibits will be compared against these profiles to identify contamination.  All instances of contamination are investigated and inform continual organisational learning.

Forensic staff who attend crime scenes are responsible for retrieving exhibits for forensic analysis and follow robust procedures based on FSR-G-206 - ‘The Control and Avoidance of Contamination In Crime Scene Examination involving Evidence Recovery’.

Once forensic exhibits are retrieved, they are sealed in ‘tamper-evident’ bags which are not permitted to be opened outside of an ISO 17025 accredited laboratory.  This is to minimise any further risk of contamination from individuals or the environment.

Organisational learning from Forensic Services is also inputted into the training delivered by Learning and Development to police officers.