Superimposition and Tattoo Mark

Superimposition

• Superimposition  helps  determine that  the  skull  is  that  of  person  in  the  photograph, by  adjusting magnification  till inter-pupillary  distances  correspond’  It is  done  by  following  steps

1. Recent  photograph  is  taken,  any  veiw-frontal,  lateral,  or semilateral  view  of  the  face’
2. Skull  is  mounted  on skull  rest.
3. The negative  of  the  photograph  and the  skull  are  superimposed  by  aligning  the  following points  that  are then compared
4. eyes  with  orbital  plates  with  two  pairs  of canthus  properly  aligned  ,
5. nasion
6. prosthion  in central  line,
7. nasal  spine
8. Iower  border  nose,
9. lower  border  upper jaw
10. zygoma  below  the  eyes’
11. supraorbital  ridges,
12. angle of  jaw
13. external auditory  meatus and teeth.

• video  superimposition  mounted  skull and  photograph  are videographed  using  a  color  camera  and the  video signals  are fed  into  a color  camera. This  digital  image  manipulation  technique  is  better.

Tatoo  marks

Tattoo marks

• Tattoo marks are designs made by multiple small puncture wounds made through the skin with needles or similar penetrating tools dipped in colouring agents ( dye ).
• Tattoos are distinctive, potentially important acquired identifying features that last for the life of the bearer, and persist into the postmortem period.
• Tatoo  marks are  designs  made  in  skin  by multiple  small puncture  wounds  with needles  or  electric vibrator  dipped  in colouring  matter’ The  dyes  commonly  used  are  lndian ink), Carbon,  indigo,  cobalt,  prussion  blue ,ultramarine,  and vermilion or  cinnabar.
• Corneal tattooing may be done with Gold chloride.
• Tattoo  mark is  permanent  when  dye  penetrates  the  dermis Infrared  photography  makes old  tattoos  readly dsible.  A  faded  tattoo  mark becomes  visible  by  use  of  utraviolet  lamp or rubbing  the  part  and examining  with  magnifying  lens.
• Marks are recognized  even in decomposed  bodies  when  the  epidermis  is  removed.  Lymph  nodes  near tattoo  mark show  pigment  deposition.

 Latent tattoo marks are faded marks and they can be visualized by

• Use of ultraviolet light
• Infrared photograpy(Blackening and tattooing of skin and clothing can be best demonstrated).
• Rubbing the part and examining under magnifying glass
• If tattoo marks are obscured by decomposition they can be visualized by treating with 3 % H₂O₂.
• Tatto marks can be developed by treating the skin by 0.5% caustic potash.
• Histopathology of local lymph nodes for pigment:- sometimes Patient’s relative gives a history of tattoo, however it is not found during autopsy then Lymph node are dissected to find it.

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