Application of Entomology in Some Medicolegal Issues

  

    
Species of    the insects 
    
Stages of    maggots 
  
  

    
1st  instar 
    
2nd instar 
    
3rd instar 
    
Post-feeding    3rd instar 
    
Total
      
No.
      
of cases    containing
      
different    larval stages
  
  

    
No.
    
%
    
No.
    
%
    
No.
    
%
    
No.
    
%
  
  

    
Chrysomya albiceps 
    
0.0
    
0.0
    
2
    
22.2
    
9
    
100
    
4
    
44.4
    
9
  
  

    
Sarcophaga species
    
0.0
    
0.0
    
0.0
    
0.0
    
4
    
100
    
1
    
25
    
4
  
  

    
Lucilia    sericata 
    
0.0
    
0.0
    
0.0
    
0.0
    
1
    
100
    
0.0
    
0.0
    
1
  
  

    
Psychoda    species 
    
0.0
    
0.0
    
1
    
100
    
1
    
100
    
0.0
    
0.0
    
1
  
  

    
Dermestid    larvae 
    
0.0
    
0.0
    
0.0
    
0.0
    
2
    
100
    
0.0
    
0.0
    
2
  

Table 7:  Percentage of distribution of larvae instars stages in examined cases in accordance to different arthropod species.

The application of entomological study was used in some cases as a representative for this study

In the studied case number one, a 7-years-old female found, in winter (November) on a heap of mud at the edge of a city in Gharbia governorate. The climatological data revealed that, the mean of maximum temperature of 15°C and the mean of minimum temperature was 9°C. The 3^rd instar larvae of Chrysomya albiceps was found on the corpse of this female. The estimated time since death was 15-16 days. This time was also compatible with that estimated during the judicial proceedings which pointed to a time of death 17 days before the body was found.

The only case in this study which was invested with Lucilia sericata. It was a young female, about 12 years old found in January (winter), in an rural area in Gharbia governorate , near a water canal coast with a rob around her neck.

During the autopsy, larvae only found in the buccopharyngeal and other natural orifices of the body (photomicrograph 9) to protect them from bad weather conditions. The age of Lucilia sericata larvae could be estimated as at least 80h from oviposition, to which a minimum of 24h before the adults arrived in the corpse should be added. Thus, the postmortem interval must be at least 4 days before the discovery of the body. In this study the judicial enquiry pointed to a time of 5 days since death, which coincided with the estimation of postmortem interval by entomological study of Lucilia Sericata.

The case number 3 was a male accidentally crushed under the wheels of a moving heavy truck in winter (February) in an agricultural area. Later in beginning of spring, after shallow burial in an old tomb with many cracks in its walls. The body was exhumed for medicolegal investigations. The body showed insect activity by both adult and immature insects (masses of larvae) all over the body. Subsequent identification confirmed the presence of Coleoptera larvae (Dermestidae), and third instar larvae of Psychoda (Diptera). Dermestidae larvae were very numerous and characteristics of the last stages of decomposition when the remains were coming to be dry. They were found in great abundance among the muscular mass and bones. The Postmortem interval estimated from entomological evidence was calculated by mainly taking into account the development of Dermestidae larvae which, takes about 22 days at 28–30°C and 40–50 days at lower temperatures. The estimated time of death was 5 weeks, with temperatures much lower than 28°C. This conclusion is congruent with the data obtained from the presence of Dermestidae larvae in the corpse. The judicial enquiry pointed to a time of death 34 days before the body was found.

The application of entomo-toxicology was used in two cases of carbamate and organophosphorus toxicity as a cause of death (case no. 12& 14 respectively).

Discussion

It is important to note that although the application of the forensic entomology has been strongly criticized for years, it is now gaining acceptance in many countries and offers a great potential of contribution to the legal profession in legal proceedings in many countries [14].

The objective of this study was to identify the arthropod species visiting the carrions, describing it and trying to correlate between decomposition processes, entomological findings and information obtained from judicial proceeding. The summarized results refer to the most important taxa for estimating the postmortem interval.

The maximum number of cases in the present study was in the age group 10-20 years (26.6%). This may be due to that teenagers are more vulnerable to violence and injuries as they are more active, trouble makers with more tendency for aggression [15]. On the other hand, the least number of cases was encountered in the age group less than ten years and more than 50 years. This may be due to the fact that this age group is less mobile out of doors and of less aggression, so, less predisposed to violence.

This study showed that, males outnumbered females (73%) and (27%) respectively with a sex ratio about 3:1. This might be due to the fact that males are more liable to injuries as they are more mobile, more violent, and more liable to be engaged in quarrels and assaults. These findings coincide with the work of El-Moslimani [16].

Arthropods observed in this study follow the same general pattern found in both tropical and temperate areas. Rapid invasion of carrions was carried by adult Diptera (especially Calliphoridae and Sarchophagidae). Four carrion-breeding dipterans (Chrysomya albiceps, Sarcophaga species, Psychoda and Lucilia Sericata) were found in this study which coincide with El- Shenawey et al. [17] who noted that Calliphoridae and Sarcophagidae larvae were the most dominant and abundant insects infesting all the carrions in all seasons as in urban and rural habitats.

Benecke [18] reported that the identification of the arthropod species found at the site of, or on a corpse, is essential but often very difficult if performed by morphological means. One reason being that the order of insects consists of more species than any other form of life which means that there are few experts for a whole insect family or insect order. Another reason for difficulty in insect determination is the minuscule morphological differences between species. In addition, the characteristics of immature larvae are sometimes extremely hard to determine. Although size of larvae can be used to determine which larval stage of development a specific species of fly is in, there is a wide range of sizes that each larval stage can have. This depends on the amount of food available to the larvae have and the ambient and maggot mass temperatures in which they develop, this is why spiracular formation is often used to determine the stage of development of a larvae [19].

On badly decomposed corpses or skeletonized human remains infested with insects, where no classical postmortem changes in soft tissues (hypostasis, cadaveric rigidity, body cooling) are available, only the entomological evidence can provide invaluable aid to the forensic pathologist for predicting the postmortem interval [20].

Interestingly, Chrysomya albiceps larvae were the most dominant and common larvae infesting 60% of the corpses and were present in all seasons except fall as well as rural and urban habitat. Therefore, Chrysomya albiceps is the most important fly species in postmortem interval estimates during death investigation in Middle Delta of Egypt.

Chrysomya albiceps is well known as a warmer species. In Europe, this species extends from southern to northen regions during hot summer. In southeastern Spain the presence of this species is extremely rare in winter [21].

Tantawi et al. [22] have noted the complete absence of Chrysomya albiceps larvae in rabbit carcasses exposed during winter in Alexandria. However, in this study the larvae of this species were found infesting two corpses at the end of the winter season when the temperature was above its normal level during this period. The previous findings were in accordance with Arnaldos et al. [11].

The duration and viability of the larval stage of Chrysomya albiceps at 18, 22, 27 and 32°C were 21.30, 10.61, 5.0 and 4.0 days with corresponding percentage of growth 76.5, 88.5, 98.5 and 99.5%, respectively [20].

The minimal duration of development from oviposition to adult was inversely related to temperature, ranging from 8.3 +/- 0.5 days at 35°C to 19.2 +/- 0.92 days at 20°C. Although eggs hatched after 1.9 +/- 0.16 days at 15°C, larvae did not complete development and frequently died during the first instar stage [21].

In the present study, out of the nine cases invested with Chrysomya albiceps, six (67%) were confined to urban and three (33%) were confined to rural areas, and the four cases invested with Sarcophaga (26%) are equally distributed between urban and rural areas (50%) for each. No habitat specificity can be obtained from this study, because, in Middle Delta of Egypt there is no distinctive discrimination between urban and rural areas. The previous findings were supported by Carvalho and Linhares [23] who found that, Chrysomya albiceps and Sarcophaga is of no value as an indicator of a particular habitat type.

The presence of only Chrysomya albiceps in most of the studied cases is due to predation of Chrysomya Albiceps on other larvae as a result of the aggressive feeding behavior of 2^nd and 3^rd stage larvae of Chrysomya albiceps clearing all earlier arrivers [24].

The third instar larvae of Chrysomya albiceps was found on the corpse of a female 7 years old in winter. The estimated time since death was 15-16 days, bearing in mind the season in which death occurred according to the study of Arnaldos et al. [11] about the samples reared in the laboratory, at a temperature over 15°C, 3^rd instar larvae of Chrysomya albiceps appear on day 3 and remain until day 13. This time was also compatible with that estimated during the judicial proceedings which pointed to a time of death 17 days before the body was found.

In this study, Chrysomya albiceps invested two cases which were buried under the ground. The mechanism by which Phorid flies could reach buried corpses could be explained as follows: adult phorid flies of genera Conicera and Metopina reach the soil depth of 50cm in four days. Also adults of the parasitic wasps of the families Braconidae and proctotrupidae occur in soil depth of at least 50cm. Conversely, bigger fly species, the larvae of which dominate in carrion covered by a thin layer of soil (e.g., Muscina species and the Helomyzid Morpholeria Kertezi Czerny), lay their eggs on the ground surface, and the young larvae migrate into the carrion through the soil [25,26].

In this study, all cases of Sarcophagidae larvae were found in spring and fall. These observations are in agreement with those of Tantawi et al. [21], who mentioned that in Giza province, Egypt, the breeding activity of Sarcophaga reaches its maximum in fall and spring.

Moreover, in summer, high temperatures suppress the breeding activity of Sarcophagidae and in winter cloudy days affect access to human remains by delaying colonization [2].

In the present study Sarcophagidae were infested 4 cases which were on the surface of the ground. On the other hand Campobasso et al. [2] founded in their study that Sarcophagidae were able to colonize rabbit carcasses buried at a depth of 10-20 cm already in March and April.

Moreover growth curves for the larvae and puparia of Sarcophaga haemorrhoidalis were studied. A significant growth of Sarcophagidae was observed at 25°C, but larvae were demonstrated under lower temperatures [27].

Surprisingly, Sarcophagidae may be the only carrion fly larvae found on a body that is physically isolated. This may reflect the fact that, in contrast to other forensically important flies, Sarcophagids deposit live larvae rather than eggs, and these may be dropped in the vicinity of the corpse when adult female cannot physically reach the body [2].

The only case in this study which was invested with Lucilia sericata. It was a young female, about 12 years old found in January (winter). In this study the judicial enquiry pointed to a time of 5 days since death, which coincided with the estimation of postmortem interval by entomological study of Lucilia Sericata. This observation was in agreement with Arnaldos et al. [11], who recorded the presence of Lucilia sericata larvae in the body of a male found in an area in south of Spain in February (winter) with similar climatic conditions. According to Kentner and Streit [28] taking into consideration the prevailing temperatures of the area and the data concerning the development of the Lucilia sericata larvae, their age could be estimated as at least 80h from oviposition, to which a minimum of 24h before the adults arrived in the corpse should be added. Thus, the postmortem interval must be at least 4 days before the discovery of the body.

Lucilia sericata is one of the earliest arriving fly species on remains with oviposition occurring typically only a few hours after death. Adult of Lucilia sericata are frequent in open and sunny habitat [29]. On the other hand Singh and Bharti [30] reported that Lucilia sericata laid eggs on human corpses discovered indoors.

In this study, Dermestidae larvae were collected from two cases (numbers 3 and 12), which were examined in spring, and their numbers were more in the highly decayed case. These findings partially in agreement with those of Kentner and Streit [28], who stated that the Dermestidae were collected during the earliest stages of decomposition in spring and summer, and their numbers increased as the remains began to dry.

In the studied case number 3, the body was exhumed for medicolegal investigations. The body showed insect activity by both adult and immature insects (masses of larvae) all over the body. Subsequent identification confirmed the presence of Coleoptera larvae (Dermestidae), and 3^rd instar larvae of Psychoda (Diptera). Dermestidae larvae were very numerous and characteristics of the last stages of decomposition when the remains were coming to be dry. They were found in great abundance among the muscular mass and bones. The Postmortem interval estimated from entomological evidence was calculated by mainly taking into account the development of Dermestidae larvae which, according to Arnaldos et al. [31], takes about 22 days at 28–30°C and 40–50 days at lower temperatures. The estimated time of death was 5 weeks, with temperatures much lower than 28°C. This conclusion is congruent with the data obtained from the presence of Dermestidae larvae in the corpse. The judicial enquiry pointed to a time of death 34 days before the body was found.

The cause of death in two cases was carbamate and organophosphorus previous studies focused on the potential use of insects associated with decomposed remains as alternate specimens for toxicological analyses. In the case of malathione poisoning reported by Guatilake and Goff [32], the development stages of both Chrysoma megacephala and Chrysoma rufifacies were indicative of a minimum postmortem interval of 5 days, whereas the victim had been seen alive 8 days prior to the discovery of the body.

To the best of our knowledge, some papers reviewed that prescription and illegal drugs and toxins can be detected in arthropods. Diptera larvae, in particular those that actively feeding on human bodies provide a potentially valuable source of information in forensic investigations especially in the absence of tissues and fluids normally taken for toxicological analyses [7].

Because the results of such studies are greatly influenced by the available number of corpses investigated, so the present study recommends that in the future many studies should be conducted on a large number of corpses to explore more the ecology and biology of carrion flies in different seasons and habitats at different areas of Egypt.

The scene of death can yield information useful to reconstruct events and circumstances, link a suspect to the victim or scene, establish the credibility of the statements made to investigators by witnesses. Therefore, the forensic entomologist should perform his work at the scene of death even after removal of the body to collect the specimens most relevant to the case study and document the ecological and environmental conditions, thus more accurate estimation of the postmortem interval could be made (Table 8).

  

    
Subj. 
    
Age by Ys. 
    
sex 
    
Resid. 
    
Time of death 
    
St. of put. 
    
Time of sample collect. 
    
Ext.wo. 
    
Amb. Temp. 
    
Gov. 
    
Cause of death 
    
Larvae distrib. 
    
Tox 
    
site 
  
  

    
Case no. 
  
  

    
1
    
7
    
♀ 
    
(Urban)
    
1/2/ 04
    
2nd
    
18/2/ 04
    
nil
    
15-9
    
Gh.
    
Smoth.
    
allover
    
nil
    
Ground surface
  
  

    
2
    
25
    
♂ 
    
(urban)
    
28/1/ 04
    
2nd
    
24/2/ 04
    
nil
    
14-8
    
Gh.
    
Myocard infarct.
    
allover
    
nil
    
Partial submer.
  
  

    
3
    
42
    
♂ 
    
(rural)
    
20/2/ 04
    
2nd
    
24/3/ 04
    
yes
    
22-17
    
Gh.
    
RTA
    
allover
    
nil
    
buried
  
  

    
4
    
18
    
♂ 
    
(urban)
    
2/5/ 04
    
2nd
    
12/5/ 04
    
nil
    
31-18
    
Ksh.
    
Strang.
    
Natural
      
orifices
    
nil
    
Ground surface
  
  

    
5
    
22
    
♂ 
    
(rural)
    
13/5/ 04
    
2nd
    
20/5/ 04
    
nil
    
30-20
    
Mnf.
    
diabetes
    
allover
    
nil
    
Ground surface
  
  

    
6
    
31
    
♂ 
    
(urban)
    
18/5/ 04
    
2nd
    
1/6/ 04
    
yes
    
34 -19
    
Gh.
    
Stab
    
allover
    
nil
    
Ground
      
surface
  
  

    
7
    
54
    
♀ 
    
(urban)
    
20/6/ 04
    
2nd
    
28/6/ 04
    
nil
    
35-22
    
Gh.
    
Myocard
      
infarct.
    
allover
    
nil
    
Ground
      
surface
  
  

    
8
    
24
    
♂ 
    
(rural)
      
 
    
3/7/ 04
    
2nd
    
22/7/ 04
    
nil
    
34-23
    
Gh.
    
Strang.
    
allover
    
nil
    
Ground
      
surface
  
  

    
9
    
17
    
♀ 
    
(rural)
    
5/10/ 04
    
2nd
    
12/10/04
    
nil
    
28-18
    
Gh.
    
Heart failure.
    
Natural
      
orifices
    
nil
    
Ground
      
surface
  
  

    
10
    
50
    
♂ 
    
(urban)
    
14/3/ 05
    
2nd
    
24/3/ 05
    
nil
    
24-14
    
Gh.
    
Ruptured aortic aneurys.
    
allover
    
nil
    
buried
  
  

    
11
    
37
    
♂ 
    
(rural)
    
23/3/ 05
    
2nd
    
3/4/ 05
    
nil
    
25-13
    
Ksh.
    
Strang.
    
allover
    
nil
    
Ground
      
surface
  
  

    
12
    
18
    
♂ 
    
(urban)
    
27/4/ 05
    
2nd
    
7/5/ 05
    
nil
    
26-14
    
Gh.
    
Carb. poison
    
allover
    
carb
    
Ground
      
surface
  
  

    
13
    
34
    
♂ 
    
(rural)
    
30/4/ 05
    
2nd
    
10/5/ 05
    
yes
    
30-18
    
Ksh.
    
Head trauma
    
allover
    
nil
    
buried
  
  

    
14
    
45
    
♂ 
    
(urban)
    
25/5/ 05
    
2nd
    
5/6/ 05
    
nil
    
32-20
    
Gh.
    
organo ph.
    
allover
    
organo ph.
    
Submer.
  
  

    
5
    
12
    
♀ 
    
(rural)
    
26/1/06
    
2nd
    
31/1/ 06
    
nil
    
12-7
    
Gh.
    
strangulation
    
Natural
      
orifices
    
nil
    
Submer.
  

Table 8:  Master table showing the case study form.