Establishing the Forensic Context - Lecture 13 Flashcards
What does “establishing forensic context” refer to?
determining if a scene has medal legal significance, ie whether what is found is relevant to a forensic case or relevant to living family members
What are the 3 questions that must be asked to establish forensic context?
- Are we dealing with bone?
- Is (are) the bone(s) human?
- Are the bones ancient or modern?
What materials can mimic the appearance of bone?
wood, stone, horn, ceramics, coral, rocks and minerals
What kinds of bone cause the most issues when trying to determine if it’s bone or not?
- fragmented bone
- heavily calcine bone (bone where the bone collagen has burned away leaving chalky white material)
What is calcine bone? When is it most commonly found?
- it is bone where all the collagen has burned away, leaving only chalky white material
- occurs in natural disasters where there are fires and explosions
What can calcine bone be confused with?
things like plaster and drywall
What are some solutions for establishing if something is bone or not?
- microscopic analysis
- chemical analysis
- morphology
Explain what microscopic analysis is and what it is used for.
- microscopic analysis uses techniques like x-ray fluorescence spectrometry (XRF) which allows you to find the chemical signature of whatever you’re looking at
- it is used to distinguish if a material is bone or not
Explain what chemical analysis is and what it is used for.
- chemical analysis uses techniques like hydrochloric acid tests where you drip hydrochloric acid on the material which won’t reach to bone
- it is used to distinguish if a material is bone or not
Explain what morphology is and what it can be used for
- morphology looks at features of the bones to identify what bone it is or if it is bone at all
- to distinguish if a material is bone or not
How can immature human bone (of a juvenile) be an issue when identifying if its human or not?
it can be mistaken as animal bones since it smaller
How can you tell if bone is immature human bone or small animal bone?
- look for unfused epiphyses and wavier texture in the epiphyses
- look for shape differences
What is the architecture of a bone referring to? How can considering it help to determine if a bone is human or not?
- it is the overall shape and size of a bone
- a bone’s architecture is determined by Wolff’s Law which is form determines function
- human have distinct shoulder, hip girdles, and spinal columns compared to animals
- the position of human foramen magnums are different from animals
What are some characteristics that are unique to human bone?
- unfused radius and ulna to allow for our arms to be more mobile
- unfused tibia and fibula for more flexible ankles
- complete fibula
- large and separate clavicles
What bones are unique to animals?
- a baculum which is a penis bone
- caudal vertebrae which is a tail
What animal paw gets mistaken for a human hand? How can you tell them apart?
- bear paw
- distal end of bear metacarpals have a groove at the head
- bear phalanges are larger and more dense
- human phalanges are long and slender
- bear’s distal phalanges are their claws
How can teeth help distinguish if what is found is human or not? What are the differences?
- teeth are also determined by Wolff’s law
- carnivores have pointed molars and premolars for tearing meat
- herbivores have broad and flat molars and premolars for chewing tough plants
- humans are omnivores and have mixed dentition
What is the difference between animal and human bone macrostructure?
animal bone is:
- denser
- less porous
- thicker in cross section
- cortical surface is smoother
How is the microstructure of animal bones different from human bones?
- human bones are made up of the Haversian system
- horses have osteon “banding” which is a mix between circular and long structures
- pigs have plexiform bones which are long thin structures
What is the timespan that dictates if remains are forensically relevant? Why?
within the last 50 years because it is still possible to get an identification and inform any living relatives and hopefully get a prosecution
How can taphonomy help establish if a bone is contemporary or not?
- taphonomy refers to the level of preservation of the bone
- the more intact a bone is, the more likely it is that the bone is contemporary since it indicates they have been exposed for a shorter amount of time
How can the colour of bone indicate if its contemporary or not?
non contemporary bone often takes the colour of what its buried in
How can texture and weight indicate if something is contemporary or not?
Texture:
- contemporary is smoother
- noncontemporary is rougher
Weight:
- contemporary is heavier due to things like fats and marrow that haven’t decomposed yet
- noncontemporary is lighter
How can the condition and fragility of the bone indicate if its contemporary or not?
Condition:
- contemporary tends to be more whole
- noncontemporary is more fragmented
Fragility:
- contemporary bone is denser
- noncontemporary is more fragile or brittle
