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SIO Corner: Open Area And Underwater Searching
This week we look at considerations needed when searching an open area and underwater
In this series we look at various aspects of life as an SIO. This includes the necessary skill sets for the successful SIO, the management of serious crime investigation and specific elements of investigative practice from initial response through crime scene examination and investigative strategies to dealing with suspects and the media. The articles are excerpts from the 2nd edition of Blackstone's, the 'Senior Investigating Officers' Handbook', written by two highly experienced SIOs (see 'About the Authors' at the end of the article).
Open Area And Underwater Searching
Open area searches encompass a wide range of environments and settings. They can include, for example, public parks and areas of public open space, farm land, woodland, landfill sites, old mining areas, remote moorland and mountainous areas, and town centre precincts.
By their nature they tend to be larger search areas than traditional localized urban crime scenes and generally do not have clearly defined boundaries. It is therefore essential that the SIO, CSM, and PolSA visit the proposed search site as part of a reconnaissance site visit and ‘walk-over’ inspection, to eg:
A balance has to be struck between ensuring vital evidence is not left outside the search area and ensuring that, for example in the case of a public park, the entire park is not cordoned off resulting in extensive resource and cost implications for cordon security and many days required searching the entire park.
Similarly, to aid such decisions the focus should be on what is being sought and using predictive modelling on where those items may be best located. Again, using a public park as an example, it may be considered proportionate to only search the paths and tracks through the park to locate and recover any evidential items discarded by an offender in their escape from the crime scene.
Search fatigue is also a relevant consideration in large area searches and research has shown that searcher focus can rapidly decrease in effectiveness if speculative line searches are conducted over large swathes of open land. Weather conditions and reduced winter daylight hours may also influence the search types and duration.
When considering searches for concealed and buried items then the use of specialist geological advice and equipment must be considered. A forensic geologist will advise on ground conditions (ie soils, rock, groundwater, and any artificial deposits) and what would be the most appropriate, cost-effective geophysical detecting equipment in that environment.
Once the choice of equipment has been identified the most effective methods for its deployment must be considered. This will be influenced by the type of instruments chosen, topography (eg is the search area flat or steep, wet or dry).
Search equipment, such as geophysical instruments, are available from many commercial and university sources but most typically from the HOSDB (Home Office Scientific Development Branch), the military and X list contractors. Additionally, police detector dogs could be utilized dependent on what items are being sought (most typically detector dogs are deployed for drugs, firearms, human blood, and remains). Both dogs and geophysical equipment do not replace a police officer searcher but greatly enhance their detecting capability.
The aim should be to use a combination of all these resources taking advice on their various benefits and limitations within the specific environment under consideration.
Once the correct choice of search instruments has been decided and the most cost-effective search methodology chosen, the suite of instruments must always be tested at the search site or crime scene. Body disposal and the burial of objects and items usually take place in soil or sediment or softer rocks. The ease by which the soil can be dug (ie its dig-ability) and placed back into the ground (or reinstated) is of importance and this can be assessed at the instrument ‘test’ or ‘control’ site.
This must be located away from the main cordon/search zone but in an area of similar and, if possible, identical geology. Representative objects should be buried at a similar depth and in the same conditions as the anticipated target. The advantages of the control site are that it:
(a) allows detections limits to be identified;
(b) provides a means to test the equipment;
(c) provides the opportunity for search officers to become familiarized in the use of the equipment before its deployment at the designated search area.
Whatever search strategy is developed, its use of specialist resources should always aim to ensure a minimally invasive search so that any surface or sub-surface evidential find can be examined and recovered by crime scene investigators and, where applicable, assisted by a forensic archaeologist where necessary (eg buried victims).
Therefore, it must be recognized that line searching and practices such as widespread strimming and raking should be avoided wherever possible due to the impact they have on vegetation.
Police dogs and geophysical detecting equipment are less invasive and any indications by either can be physically confirmed as evidential finds by a police search team officer.
Trained forensic geologists may be able to observe and identify any subtle ground disturbances and suggest whether these may have been caused by natural processes or digging and the reinstatement of the displaced soil.
Detective Superintendent Tony Cook was a CID officer with Greater Manchester Police for over 31 years until his retirement in 2009. During his time as an SIO, he led a number of high profile investigations including operations into gangland violence at Moss Side, the Bolton murder of a teenage girl in 2002, and the Denton strangling case. He was a trained assessor for promotion and a qualified Authorising Officer under RIPA. Tony received 14 commendations and a first-class BSc Honours degree in social sciences and a Diploma in Social Policy & Criminology from the Open University.
Andy Tattersall, formerly Detective Superintendent in Greater Manchester Police on the Force Major Incident Team, retired in 2007 after 33 years service and became the first ever Support Staff SIO in charge of a new Homicide Support Unit. With over 29 years in CID at all ranks Andy received the Homicide Working Group National Award for his Outstanding Achievement in the Field of Homicide in November 2006.
To see more details about the Senior Investigating Officers' Handbook, or to purchase a copy, click here
