CORPSE

FIELD OF THE INVENTION

This invention relates to apparatus for estimating post-mortem interval of a corpse, particularly a human corpse.

BACKGROUND TO THE INVENTION

When forensic pathologists are called to investigate a death one of the most critical tasks is that of estimating the post-mortem interval, or time of death, of the corpse. Pathologists will typically make use of one of a number of methods to determine the post-mortem interval. One of the most frequently used methods entails measuring the core body temperature and correlating this to the time of death using a temperature-time graph, or derivatives thereof. This method is does not take into account prevailing weather conditions, such as wind (speed) and relative humidity, which may affect the rate of cooling. Other methods of estimating the death interval tend to focus on the increase or decrease of certain chemicals in the body after death. These methods require that samples must be taken and sent to a laboratory for analysis. Also, sophisticated, expensive equipment is often required to conduct certain analyses which may not be readily available to many forensic pathologist laboratories.

Once the core body temperature reaches ambient temperature, and particularly after decomposition commences, it becomes impossible to determine post-mortem interval using temperature-based methods. Even chemical-based methods become unreliable because tissue breakdown either drastically alters the concentration of such chemicals, or no tissue is left to sample from. In these circumstances pathologists typically visually assess the state of decomposition and use their judgement to correlate their findings to expected decomposition after a period of time. This method provides a very rough estimate at best and, because of its subjective nature, suffers from even greater inaccuracies than the core body temperature method. Clearly, the rate of decomposition will vary according to the environment in which the corpse is located. For example, decomposition will be faster outdoors in a hot and humid climate than indoors in a cooled atmosphere. Thus, the inaccuracies of this method of post-mortem interval estimation are compounded. OBJECT OF THE INVENTION

It is an object of this invention to provide apparatus for estimating the postmortem interval of a corpse which will at least partially alleviate some of the abovementioned problems.

SUMMARY OF THE INVENTION

In accordance with this invention there is provided apparatus for estimating the post-mortem interval of a corpse comprising a portable processor which can communicate with at least one of a body temperature sensor and a sensor for measuring tympanic membrane temperature, and wherein the processor is configured to calculate an estimated post-mortem time of a corpse as a function of the measurements obtained from the at least one sensor, and to provide the estimated post-mortem time to a user thereof.

Further features of the invention provide for the processor to further communicate with a sensor for measuring potassium ion (K ⁺ ) concentration in the vitreous humour; for the processor to also communicate with one or more of an atmospheric temperature sensor, an air velocity meter and an atmospheric humidity sensor; for the processor to further be capable of communicating with a store of historical meteorological information relating to the area in which the corpse is located; for the meteorological information to include one or more of air temperature, wind speed, precipitation and atmospheric humidity for a period of time preceding use of the processor; and for the processor to communicate with a GPS unit to obtain the location of the corpse.

Still further features of the invention provide for the processor to provide on a display a progressive visual depiction of typical decomposition of a corpse over time and means for a user to stop the progression when a depiction matches the observed extent of decomposition of the corpse, and an output of estimated time of death based on the selected depiction; and wherein the processor depicts the rate of decomposition as a function of one or more of measured atmospheric temperature, measured air humidity and historic meteorological information relating to the area in which the corpse is located. Yet further features of the invention provide for the processor to communicate through a wireless protocol with the sensors remote therefrom; for the body temperature sensor to include a probe insertable into the abdominal cavity or rectum of the corpse; for the sensor for measuring potassium ion (K ⁺ ) concentration in the vitreous humour to include a probe insertable through the sclera into the anterior chamber of an eye of the corpse; and for the sensor for measuring tympanic membrane temperature to include a probe insertable into the external auditory meatus of an ear of the corpse. Further features of the invention provide for the at least some of the sensors to include a processing and transmitting unit which is removably secured to the probe; and for the probes to be disposable.

The invention also provide a processor configured to provide on a display a progressive visual depiction of typical decomposition of a corpse over time with means for a user to stop the progression when a depiction matches the decomposition of the corpse, and for the processor to calculate an estimated post-mortem interval based on the selected depiction.

Further features of the invention provide for the processor to calculate the estimated post-mortem interval taking into account a measured atmospheric temperature; and the processor to take into account further environmental factors when estimating the post-mortem interval.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:-

Figure 1 is schematic diagram of apparatus for determining the postmortem interval of a corpse.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

One embodiment of apparatus (1) for estimating the post-mortem interval of a corpse (3) is shown in Figure 1 and includes a portable, handheld device (5) which has a processor (7) and a large touch operated display screen (9). The device (5) is capable of communicating through a wireless protocol, in this embodiment Bluetooth, with a number of sensors (1 1 , 13, 15) and has a global positioning system (GPS) facility (17). The device (5) is also capable of establishing a wireless connection to a communications network (19), in this embodiment through both GPRS and WiFi. The communications network (19) could be a public network, such as a cellphone network, or a private network.

The device (5) further has a temperature sensor (21), a relative air humidity sensor (23) and an air velocity meter (25) for measuring wind speed. In this embodiment the air velocity meter (25) includes a set of blades (26) mounted on a hub (27) which is rotatably secured within a passage (28) extending through the device (5) at the upper end thereof. However, any other suitable device can be used, including electronic devices.

The sensors (1 1 , 13, 15) in this embodiment include a core-body temperature sensor (1 1 ), a tympanic membrane temperature sensor (13) and a potassium ion (K ⁺ ) concentration sensor (15). Each of the sensors (1 1 , 13, 15) is constructed to have a probe (31 , 33, 35) which is releasably secured to a body (41 , 43, 45), each of which houses a small processor, Bluetooth transceiver and rechargeable battery acting as a power source.

The probe (31 ) of the core-body temperature sensor (1 1 ) is a thermocouple which is suitable for insertion through a small incision into the abdomen (46) of the corpse (3), or into the rectum. One end (47) of the thermocouple (31 ) is releasably secured in a complementary socket in the body (41 ) and a radially extending flange (49) is provided about the thermocouple (31 ) adjacent the end (47) to limit the extent to which the tip (51 ) can be inserted into the corpse (3).

An infrared ear probe (33) suitable for insertion into the external auditory meatus (52) is similarly releasably secured to the body (43) of the tympanic membrane temperature sensor (13).

The probe (35) of the potassium ion concentration sensor (15) is a needle- shaped electrode which is potassium ion selective and can be inserted into the anterior chamber of an eye of the corpse (3) through the sclera (54) to measure the potassium ion concentration of the vitreous humour. Similarly to the core-body temperature sensor (1 1), the electrode (35) is releasably secured to the body (45) and has a flange (55) adjacent the body (45) to limit the extent to which it can be inserted into the eye.

In use, a forensic pathologist (not shown) will activate the device (5) upon arriving at the scene of an incident. Each of the sensors (1 1 , 13, 15) will be activated and calibrated if necessary, and thereafter a message on the screen (9) will prompt the pathologist to locate each appropriately on the corpse (3). Thus, the thermocouple (31 ) of the core-body temperature sensor (1 1) will be inserted through a small incision in the anterior abdominal wall of the corpse (3) into the sub-hepatic space. The tip (51 ) of the thermocouple may be sharpened to obviate the need for an incision to be made using a scalpel or other instrument. The infrared probe (33) is inserted into the external auditory meatus of one ear of the corpse (3) and the electrode (35) inserted through the sclera of one of the eyes.

In the interim, the device (5) automatically starts measuring ambient temperature and humidity using the temperature sensor (21 ) and relative humidity sensor (23). The device (5) also automatically activates its GPS facility (17) and determines the coordinates of the scene. Thereafter, the device (5) opens a GPRS connection through a cellphone network (19) to the Internet (60) whereafter it accesses a data base (62) containing a store of historical meteorological information. Using the coordinates provided by the GPS, data recorded for the past 36 hours by the meteorological station closest to the location of the corpse (3) is downloaded. The meteorological information includes air temperature, wind speed, precipitation and atmospheric humidity for an immediately preceding period of time.

If the corpse (3) is outside and a wind is blowing or inside and is subjected to air movement, such as from a draft from an open window or from a fan or air conditioning unit, the forensic pathologist uses the device to measure the air velocity over the corpse with the air velocity meter (25).

Once the sensor readings have stabilised, the temperature and potassium ion concentration measurements made by the sensors (1 1 , 13, 15) are transmitted to the device (5). The processor is configured to calculate an estimated post-mortem time of a corpse as a function of the measurements obtained from the sensors (1 1 , 13, 15) and does so using algorithms similar to those conventionally used for this purpose, such as by comparing the measured values with known values for any given post-mortem interval. The Marshall and Hoare two-exponential equation is an example of an algorithm that is known for estimating the time since death. Importantly, however, the algorithms are modified to take into account the measured meteorological conditions, being ambient temperature, relative humidity and wind speed. The algorithms also take into account the historical meteorological conditions obtained from the data base (62). In this way the meteorological conditions which greatly affect the rate of cooling of a corpse are taken into account in estimating a post-mortem interval for each of the measurements taken on the corpse. The algorithms may also take into account clothing on the corpse and its degree of wetness, both of these factors affecting the rate of cooling of the corpse. To this end processor (7) could be configured to prompt the user to input this information. The processor (7) subsequently indicates the estimated post-mortem time based on the measurement from each of the sensors (1 1 , 13, 15) on the screen (9).

Still further, the processor (7) is configured to provide an estimated postmortem time based on all of the measurements. The algorithm used by the processor (7) to provide the estimate may make use of a weighting or a statistical significance attributed to each measurement.

The sensors (1 1 , 13, 15) can also be left in position on the corpse for a period of time and measurements recorded over the time period. This allows rates of cooling to be obtained for the temperature sensors (1 1 , 13) and a rate of change of potassium ion concentration to be obtained for the sensor (15). These rates of change can be used by the processor (7) to assist in calculating the estimated post-mortem interval, or to correlate with its calculated rates of change.

The estimated post-mortem interval can be displayed on the screen in any suitable manner including in the form of a plotted nomogram, a graph with the measured variable in the Y axis and the post-mortem interval in the X axis, and a simple time or time period and date.

All information can be transferred from the device to computer or other suitable device if required.

The apparatus (1) shows great improvement in estimating post-mortem interval over currently employed methods of doing so especially as the risk of obtaining erroneous measurements is greatly reduced by taking more than one measurement and in that meteorological conditions are taken into account in calculations.

Where the temperature of the corpse (3) is close to or the same as the ambient temperature, or after decomposition has commenced, it becomes extremely difficult, or impossible, to calculate post-mortem interval on this basis. In these circumstances, the device (5) can be operated to display on the screen (9) a visual depiction of the typical progression of the decomposition of a corpse. In addition the depicted progression contains additional time-expected findings such as sequential colonisation of the corpse by different waves of necrophageous insects or maggots, and continues to the stage of complete skeletinisation or mummification, the eventual ending depending on the measured atmospheric temperature, air humidity and historic meteorological information relating to the area in which the corpse is located. The pathologist is able to compare the state of decomposition of the corpse (3) to that depicted and when a depiction approximately matches the state of decomposition of the corpse (3) the pathologist is able to stop the progression by, in this embodiment, tapping on the display (9). When the progression is stopped, additional information about key expected findings in the form of text or illustrations is displayed to the pathologist on the screen on top of the depiction. The processor (7) then calculates an estimated post-mortem interval based on the state of decomposition selected. In performing its calculation, the processor (7) takes into account the measured meteorological information. This is particularly useful where the corpse is indoors and where ambient temperature and humidity fluctuations are generally much less than outdoors and hence the rate of decomposition more uniform.

Discrepancies in the rate of observed decomposition with the rate of decomposition depicted, especially in indoor environments, could potentially point towards the body having been moved to a different location after death, tampering with the insulation on the corpse or tampering with the heating or cooling of the room after death.

The processor (7) can also be configured to take into account historical meteorological information obtained from the database (62) and information relevant to the location of the corpse (3). The latter would include information relating to the environment known to affect the rate of decomposition. For example, a corpse located in or near sewage will decompose faster than it would otherwise have and this can be taken into account in calculating the rate of decomposition. To enhance accuracy, once the user has made an initial selection further more detailed depictions of progressive decomposition may be provided for the user to choose from. It is also envisaged that the user will be able to scroll backwards and forwards through the depictions during the selection process.

The apparatus (1) thus permits a more accurate and objective estimation of post-mortem interval by simple visual analysis as it takes into account environmental factors. It is envisaged that the processor may also be configured to use image recognition technology to analyse an image of the corpse illustrating its decomposition and so estimate the post-mortem interval. Clearly the image could be taken using a camera associated with device or simply be transferred to the device. The probes (31 , 33, 35) of the sensors (11 , 13, 15) may be disposable to reduce the risk of infection to the user thereof, and can be of any suitable configuration. These could be detached from their respective bodies and left in position on the body until they can be safely disposed of, or removed and appropriately disposed of at the location of the body. The sensors will preferably have a self-calibration facility but may also be supplied with means for calibration prior to use. Also, the sensors need not communicate with the device wirelessly and could have a wired, or any other suitable connection if desired. For example, the sensors could be configured to record information and transfer this to the device upon being removed from the corpse and inserted in to an appropriate socket on the device.

Furthermore, it is not necessary that the device communicate with the three sensors described above. It could communicate with more or less sensors if desired and also depending on the state of the corpse.

It will be appreciated that many other embodiments of apparatus for estimating the post mortem interval of a corpse exist which fall within the scope of the invention. For example, a laptop computer, PDA or suitable cellphone could be configured through software to communicate with the sensors. A portable meteorological station locatable adjacent the corpse could also be provided to measure temperature, relative humidity and wind speed and communicate these to the device. Clearly, where the corpse is in a state of decomposition a laptop computer, PDA, cellphone or other device could be used to depict typical progressive decomposition and estimate a post mortem interval as described above, preferably using an ambient temperature provided by the user thereof. It will further be appreciated that the algorithms used by the apparatus may be specific to geographical regions or even populations. For example, cooling of a corpse of a typically overweight population in a mild climate will be different to that of a normal to undernourished population in a tropical climate and the algorithm used should take these factors in to account. The device may also provide the user with a selection of algorithms to use, and these may require the user to input information relating to the corpse, such as its weight, height, build and the like. Alternatively, the device could obtain such information by using image recognition technology.

It will further be appreciated that the processor (7) could obtain measurements of the core body temperature through any other known means apart from the insertable thermocouple or tympanic membrane probes, including the use of high-sensitivity infrared cameras or similar technology.