The liquid is sprayed on the intruder if he attempts to force entry by breaking the door chain on the front or rear door.
Chain Reaction, distributed by StranDNA (Ltd) in association with Silent Technologies Ltd, is a device based on the conventional door chain principle.
In the basic “Silver” model, if an intruder breaks the chain by force against the door, it emits a 138dB screech alarm.
In the “Gold” version it also sprays a trace element of clear non-toxic substance from a pressurised canister. This is visible under ultra violet light.
This has a unique DNA code and will remain on clothes and skin for weeks.
The code is held in a database linking it to the property.
If the device is activated by an attempt at forced entry, a StranDNA representative will replace it, put the discharged unit in an evidence bag and forward it to analysts.
If an arrest is made and a suspect found to be stained with the liquid, forensic scientists are able to establish its unique code linked to the property.
Sales director, Robert Simpson said that anyone could buy and fit the alarm-only version but for the DNA trace version to be recognised by ACPO as providing evidence in court it had to be professionally installed by a recognised company representative.
He was setting up a list of professional installers throughout the UK. Training sessions will be held.
The device could also be used to protect garden sheds or caravans.
Although the trace element would remain on the skin or clothes for weeks, the length of time depended on exfoliation of skin and the number of times clothing is washed.
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