Crime Scene Investigation

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Crime Scene Investigation

• Forensic scientists collect evidence from present
  crime scenes in the aim of finding perpetrators
  of crime
• They collect small samples of evidence left
  behind at the scene and use them to reconstruct
  events that led to the crime occurring.
• Use some investigative skills to solve the
  following crimes
• INK PEN MURDER
• WHO STOLE THE SWEETIES?

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• Ink Pen
• Murder

• We have reason to suspect dirty deeds at work!
• Mr Scribbler, the chief animation assistant, on
  the new Disney film was found murdered at his
  drawing board late last night.
• The murder weapon is thought to be a pen, as the
  only clue left behind was a pool of ink and ink
  stains on Mr Scribblers shirt.
• Our only hope, in the form of Mr Labcoat, our
  resident scientist, has gone on holiday for two
  weeks and we need to track a our culprit before
  he strikes again!
• My only hope is to ask you, our new forensic
  science recruits, to solve the mystery of the
  Ink Pen Murder.
• Take the challenge!!!!!!!!

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Chromatography

• Using a separating technique called
  chromatography, we might just be able to find
  the murderer from our list of suspects.
• We can use chromatography to separate very small
  quantities of substances, which vary in different
  solubilities in different solvent.
• Using a special type of paper called
  chromatography paper, which you can put the
  substances onto, and by placing the paper into a
  solvent, the different substance will separate on
  the basis of how well they dissolve in the
  solvent.

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How it separates inks

• Ink from pens usually contain different types of
  dye, which make up the colours. These dyes have
  different solublities in the solvent. Those,
  which are the most soluble in the solvent, travel
  the furthest, carried by the solvent and coloured
  traces can be seen.
• This indicates that if we can find exactly the
  same chromatogram using a range of inks from our
  suspects we will be able to work out who the
  murderer is, by comparing it to one carried out
  by Mr Labcoat on the sample found at the scene
  before he left.
• The instructions on how to carry out this
  investigation can be found opposite, should you
  chose to except the mission.GOOD LUCK!!!
•  
• Inspector Gadget

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You will need

• !    Safety goggles
• !    A piece of chromatography paper
• !    A beaker containing a solvent to run the
  chromatogram
• !    Evidence inks from suspect A, B, and C
• !    Sample of ink found at the crime scene
•  
• ! SafetyEthanol, which is used in the solvent,
  is highly flammable and harmful. Take care when
  using it.

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To carry out the investigation, follow these
instructions

• !    Place the chromatography paper on the bench
  in front of you. Using a ruler and a pencil draw
  a line across the bottom of the paper 2cm from
  the base. Make sure this line is parallel.
• !    Using a pencil mark four dots on the line,
  evenly spaced out.
• !    Put your three samples from your suspects on
  the first three dots, a small drop will be enough
  and then the sample of ink from the scene of the
  crime on the last spot. Mark at the top which
  sample belongs to who, for your own reference.
• !    Stand the paper in the solvent and let the
  solvent run until it has almost reached the top.
  (See the diagram on next page).
• !    Lift out the chromatography paper and leave
  it to dry.
• !    Compare the evidence and solve the mystery.
  If the traces match.then they are the murderer.

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Finger prints

• No one has the same finger prints
• as you!

Use the ink pad, to roll one finger at a
time across the ink pad then carefully roll it
across the paper