The DNA Databanks

dna-giphyIn 1995 Parliament passed the Criminal Investigations (Blood Samples) Act (New Zealand). It established the National DNA Profile Databank. New Zealand was only the second country in the world to create a DNA profile databank.

The Institute of Environmental Science and Research (ESR) operates the National DNA Profile Databank on behalf of Police. The Databank contains DNA profiles of people convicted of certain criminal offences that are punishable by imprisonment. In most cases these profiles are kept on the Databank forever.

The Databank also contains the DNA profiles of people who have agreed to have their profile stored on the Databank.1 In this situation, the person’s DNA profile stays on the databank until/if the person asks for Police to remove their profile.

Since 1995 the Databank has grown steadily.  There are now more than 185,000 profiles from individual people on the Databank.

On behalf of Police, ESR also maintains a Temporary Databank of some DNA profiles. These are DNA profiles produced from DNA samples (see “DNA samples and DNA profiles”) obtained by a police constable from someone they have arrested or intend to charge with an imprisonable offence.2 The law says the DNA profiles produced from these DNA samples can be held on the Temporary Databank. If the person, whose DNA sample is obtained, goes on to be convicted of the offence for which they were arrested (or a related offence), then the DNA profile will be transferred from the Temporary Databank to the National DNA Profile Databank.3

There is a further database that is maintained by ESR – the “crime scene database”. When unknown DNA is found at a crime scene (that does not belong to the victim, nor to other people eliminated from the investigation), then ESR may choose to upload the DNA profile produced from that unknown crime scene DNA sample to the crime scene database.

By comparing the profiles in the crime scene database against the National DNA Profile Databank and the Temporary Databank possible suspects can be identified. ESR’s statistics reveal that nearly 75% of all unsolved crime profiles loaded to the crime scene database result in a link to a profile held on either the National DNA Profile Databank or Temporary Databank. These links produce valuable leads for unsolved cases.

Crimes can also be linked together. Nearly a third of all crime sample profiles loaded to the crime scene database link to another profile on the crime scene database.

There are currently around 36,000 crime scene sample profiles in the crime scene database.

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  1. Under Part 3 of the Criminal Investigations (Bodily Samples) Act 1995. (For more information see "When Police can obtain DNA samples” and "How long Police can keep DNA samples and DNA profiles").
  2. That is, an offence for which the person can be punished by a term of imprisonment. Although the law says police officers can obtain a DNA sample from anyone who has committed an imprisonable offence, in practice police officers tend to obtain DNA samples from people who have committed more serious offences, not just any imprisonable offence.
  3. These DNA samples obtained on arrest or intent to charge are authorised under part 2B of the Criminal Investigations (Bodily Samples) Act 1995. Part 2B was added to the Act in 2009. This Part also added the Temporary Databank. (For further information on when and how samples are obtained see “When Police can obtain DNA samples”. For information on how long Police can keep the DNA profile on the temporary databank in other situations, or how long they can keep the DNA sample, see  “How long Police can keep DNA samples and DNA profiles").