Advancements in Predicting Deposition Time of Bloodstains: A Comprehensive Review

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Introduction

Bloodstains are the valuable evidence in forensic science as it is most commonly found in cases of violent crimes like murder, Terrorism, Riots etc. In this decade, as the rate of crime increases day by day due to various factors like poverty, unemployment etc. at the crime scenes, therefore there are greater chances to find the traces of blood as an evidence. Investigating the Traces of blood or the Bloodstains found at the crime scenes is of prime importance to the forensic investigators.

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Forensic Investigators need to answer the following questions : what trace is it? Is it humans or animals trace ? if it is humans then which one is this , Why is it here ? How long an event last? or when did the event occurs? To answer the above questions reliable methods have been successfully implemented to identify the particular stain that is Blood or not, to confirm the species of origin i.e animal or humans, to individualize an individual from number of suspects.

That is the proof of the presence of particular Individual at the crime scene. However, to determine when did the trace being left at the crime scene, there is no reliable, robust method have been established till now even after studies of 100s of years. Scientists constantly working on this field to achieve success. Therefore, there is requisite to study and compile studies that have done till now to help the researchers for further investigations.

Bloodstains are composed of Red Blood Cells, White Blood Cells and plasma .

The studies on the Red Blood Cells shows correspondence with time includes the techniques like Atomic Force Microscopy, Oxygen Electrode , Electro paramagnetic Resonance etc. The studies on the alterations in the White Blood Cells which contain DNA and RNA where DNA doesn’t change with time and RNA degradation correlates with the time. Plasma includes assays based on the changes in the enzymes levels bio catalytic assay and bio affinity based assay.

Importance of predicting the deposited time of bloodstains is that it reconstruct and analyse the sequence of events that have happened at the scene of crime by critically examining the patterns of bloodshed events. It can assess the affirmation that is declared to be true. It take the Investigation to the next level in the right direction.

For the analysis of Bloodstains deposition time, there are a lot of methods or techniques that have been developed. In Forensic Investigation we move from non-destructive to destructive methods to avoid loss of samples. Among all of the techniques some are destructive in nature , some are non-destructive, which some are semi destructive from which mostly are short term, few are very short term and few are long term methods to determine the deposited time of bloodstains. Recently spectroscopic methods along with Chemometric methods are utilised to enhance the accuracy rate. Nowadays, Smartphones are also the subject to study the deposition time of bloodstains.

The main focus of this study is to investigate the recent developmental studies and find most relevant studies for the on - site applicability of the techniques to predict the deposited time of bloodstains in real time and to came across the limitations of the various techniques so as to bring modifications in that to enhance the precision and get the reliable, robust, reproducible methods that came under dauberts standards.

Review of Literature

Matsuoka etal.(1995) : The use of oxygen electrode has been attempted to predict the deposited time of bloodstains. The colorimetric analysis were conducted to ascertain the total Hb in the deposited Bloodstains. And with the Oxygen electrode being dipped into water, the amount of oxygen in the blood was considered to predict the deposited time of bloodstains. The fraction of Oxyhaemoglobin to Total Hb has been explored for 10 days and deduced the results that the Oxy Hemoglobin varied with time.

Fujitaetal.(2005) : In this current study, The technique named Electro paramagnetic resonance that calculated the extent of hemoproteins has been adopted to predict the deposited time of bloodstains. This technique fabricates the bloodstains with the components including ferric High spin, ferric nonheme ,ferric low spin and ferric radicals that gave rise to the signals g = 6.2 (met- Hb), g4= 4.3,H= 2.27 (hemi chrome) and R = 2.005. The correspondence of free low spin to ferric non heme i.e H/ g4 were evaluated for one and half years, which deduced from the analysis that the Electro paramagnetic resonance flashed a great accuracy for only two months.

Guoetal.(2012): This study examined role of the Fluorescence lifetime to predict the deposited time of bloodstains. Fluorescence lifetime states the time at which the electrons stays in the excited state. Based on the alterations in the Tryptophan level, the fluorescence lifetime changes with time. The analysis concluded that this is a valuable tool to predict the deposited time of bloodstains for one week with great efficiency. Fluorescence lifetime fabricated the reasonable, reliable and expeditious results.

Edelmanetal.(2012) : This study investigates the possibility of Hyperspectral imaging to predict the delivered time of Bloodstains. The experimentation adopted duplicated crime scene to observe the functionality in actual crime scene. After the 200 days of analysis of fractions of Hb derivatives by documented the visible reflectance spectra of bloodstains, the error rate was found to be 13.4%

Li etal.(2013) : In the Current Study, Hyperspectral imaging method was adopted to observe the visible reflectance spectra of Hemoglobin derivatives of Bloodstains and was analysed for one month with the use of linear discriminant model to predict the deposited time of bloodstains. The Linear discriminant analysis has been used to realize the correlation between the time of deposited Bloodstains and visible reflectance spectra. Recently deposited bloodstains for 24 hr was evaluated for the first time with an error of 0.09 hr. Accurate results were analysed for the period of one month with an error of 1.17 days.

Huimin Sun etal.(2017) : They worked on visible reflectance spectroscopy along with three Chemo metric methods to precisely predict the deposited time of bloodstains. After the deposition of bloodstains on any substrates, the colour of the bloodstains were found to be altered within different periods of time due to denaturation of hemoglobin. They used Partial Least Square Regression & Principal Component Regression model were used to measure and analysed the spectroscopic data. And LSSVM for pattern regression. This study has been performed at a constant temperature of 37°C and 10% humidity for 45 days at various time intervals the results were evaluated. The results from the analysis concluded that the (LSSVM) Least Square Support Vector Machine and (PLSR) Partial Least Square Regression model were the highly efficient methods with greater precision. The visible reflectance spectroscopy along with were found to be reliable method to estimate the deposited time of bloodstains.

Kyle etal. (2017) : He worked on a non-destructive and long term method to predict the deposited time of bloodstains. With the use of technique Raman Spectroscopy, the spectra were observed carefully and found that there were alterations in the spectra which were coordinated with the chemical processes happened in the bloodstains as the time since deposition proceeds therefore, it could predict the deposited time of bloodstains. By critically examined the spectra, they concluded that there were 70% accuracy rate to predict the deposited time of bloodstains.

Lin etal.(2017) : this study used the ATR- FTIR along with three chemometric methods as an application in predicting the time since deposition of bloodstains. They formed the bloodstains on interior conditions and environmental conditions to simulate it with the physical condition that could be present at the scene of crime. Two partial least square discriminant analysis models were critically examined which furnished the principal information in reconstruction of crime events that can differentiate between recently deposited bloodstains and stains deposited for a longer time for 0.25 -7 days. And they deduced the analysed results with partial least square regression models for 7-85days furnished the consistent results.

Smijsetal. (2018): In this Current Study, Force Spectroscopy has been utilised, based on the temporal modifications ascertain the degree of alterations in the physical properties like Elastic Modulus, Adhesion forces, Energy dissipation and dielectric properties of bloodstains. They assessed the alterations that occurred in the RBCs flexibility by Force spectroscopy. After the critical analysis, It has been deduced that the Young modulus established the correspondence with time progressed.

Caddet.al.(2018) : In this experimental study a modern method, the visible wavelength reflectance and hyperspectral imaging has been utilised to predict the deposited time of Bloodstains. This study established on unique absorption spectrum in the region(400nm-650nm) In this study, manufactured the 9 fingerprints with stains of blood on white ceramic tiles and investigated the results with the regular intervals on generated 30 days calibration and 24 hour calibration with HSI. The spurious colourageing calibration which produced the Red Green Blue colour as the age proceeded. The Results concluded that the monitored alterations on recently deposited bloodstains were more than older deposited Bloodstains.

Wang etal.(2019) : This Study introduced the applicability of LIBS (Laser Induced Breakdown Spectroscopy) to determine the deposited time of Bloodstains. They Used the Laser Induced Breakdown Spectroscopy on Four varied surfaces mainly observed at the crime scene Stone brick, Ceramic tiles, Copper plates and steel plates for the study. Based on the presence of Iron element in the bloodstain evaluated the correspondence of the single line intensity with the deposited time of Bloodstains. It has been explored that the Pearson’s correlation coefficient was found to be r = 0.99024, which means stronger accuracy rate above 70%

Wooseokchoietal. (2019) : This Study based upon the pattern detection of pictures of the bloodstains taken at different Drying time. With the use of fact that Drying process of bloodstains varied with time, gave the clue to predict the deposited time of bloodstains. To study the captured picture of bloodstains on smartphone three detection systems were used which are blood pool, crack ratio and colorimetric analysis. With these the patterns was detected by the system for two days and established precise results with amplified picture of a greater resolution.

Discussion and Conclusion

Matuoska etal. utilised a short term method with Oxygen Electrode, which explored the correlation of Oxyhaemoglobin and total hemoglobin with time and found that the decay rate of Oxyhaemoglobin directly proportional to the time. EPR technique used for the First time by (Fujitaetal.) that shows correspondence with free low spin to ferric non – heme for 270 days , accurate results were found for only the time period of 60 days. On the basis of variations in the levels of Tryptophan (Guoetal.) used FLT that changes with a very short period of time that can be used to differentiate between the fresh and older Bloodstains. (Edelmanetal.) used the HSI method that is a long term with non destructive nature, examined the visible reflectance spectra of Hb derivatives for 200 days with an error rate of 13.4%. (Li et.al.) used Hyperspectral imaging along with Linear discriminant analysis for the analysis and accurate results were evaluated for a period of one month with an error of 1.17 days which means the accuracy increased with the application of LDA. later (Caddet.al) utilised the visible wavelength reflectance along with HSI and found that the alterations monitored on the recently deposited Bloodstains were more than older deposited bloodstains.(Huimin Sun)et.al used visible reflectance spectroscopy along with three chemometric methods (LSSVM , PLSR , PCR) and found LSSVM and PLSR were highly efficient with precision. Visible Reflectance Spectroscopy along with LSSVM works best and considers this as a reliable method to predict the deposited time of bloodstains.

Lin et.al used ATR -FTIR technique along with PLSR were found to be accurate and reliable method for 7-85 days). It can differentiate between the fresh and older deposited Bloodstains for 0.25- 7 days. ( Smijsetal ) used AFM , a little invasive method assessed the alterations in the flexibility of the RBCs and found increased trends in the Young’s modulus with time. ((Wang et.al.) used a novel technique for age determination of bloodstains, LIBS being fast Analysis, a little invasive which is applicable to be used at the scene of crime. LIBS correspondence were observed with single intensity line and time of predicting Bloodstains.( Choiet.al.) Smartphones being portable, easy to use were used with three detection systems with which precise results were evaluated in 48 hours with amplified pic with high resolution.

After the analysis of all the papers, it is concluded that most valuable and reliable technique till now is using HSI, as it is a method when combined with LDA, only 1.17 days error were found and when combined with Visible wavelength reflectance the accurate results were evaluated only for the recently deposited Bloodstains. Being non- destructive this is a good method to determine the deposited time of Bloodstain but still needs more work on development of portable instrument and also on the effects of environmental factors. After that nowadays, a novel approach is to use Smartphones to predict the deposited time of bloodstains has been introduced, which is non destructive, portable, easy to use even without the need of professionals. Precise results were analysed for 48 hours , still requisite to establish the software for analysis which can also Study effect of the environmental factors. There are some techniques which are short term some which are long term, but mostly it was found that the precision decrease with increasing time of deposited Bloodstains.

There are some Technique which found useful to differentiate between the recently deposited Bloodstains and the older ones which including Hyperspectral imaging, Smartphones, Fluorescence lifetime, Raman Spectroscopy, Near infrared spectroscopy etc.

Laser Induced Breakdown Spectroscopy is a reliable method, a little invasive method has practicability as it used the background surface similar to the one that most frequently encountered at the crime scene. It can predict the deposited time of bloodstains with precision of 70%

In modern world, the researchers attracted to work on the use of Chemometric methods (LSSVM has highest accuracy rate, PLSR has higher accuracy rate and PCR has lesser accuracy rate) to predict the deposited time of Bloodstains Which are little invasive but the results gets with higher precision. Visible reflectance spectroscopy along with LSSVM were found to be a reliable method to predict the deposited time of bloodstains. similarly PLSR has been used with the ATR -FTIR spectroscopy for 7-85days, which utilized the interior and exterior environmental conditions to simulate the real time condition’s and furnished the reliable results.

Futuristic approach should be based on the reliable method that has applicability of the technique to use at the crime scenes which will be possible when Analysing the different environmental conditions( including substrates effect , temperature , humidity ) to simulate real time conditions while till now most studies were done under stored conditions that does not gives values to the practicalities of the techniques.