Mystery Writer's Guide to Forensic Science: Collecting Evidence IV

Over the next few weeks, we're going to be discussing the collection of evidence at a crime scene. I've decided to list things to collect and how to collect them alphabetically. This week in the alphabet of crime collection, we will be examining letters:

G - I

Glass

(at the scene)

• Shoes and clothing of suspects or other objects contaminated with glass should be wrapped in paper and submitted to the Laboratory for examination.
  
• All glass found at hit-and-run scenes should be recovered. The search should not be limited to the point of impact, since headlight glass may be dropped off at some distance away as the car leaves the crime scene. Glass from different locations should be kept in different containers. All glass should be collected because more than one type may be present. In addition, if just a few representative samples are saved, individual pieces that could be physically matched with glass remaining in the headlight shell of the suspected vehicle may be overlooked.
  
• Place small glass fragments in paper bindles, then in coin envelopes, pill boxes, or film cans which can be marked and completely sealed.
  
• Place large glass fragments in boxes. Separate individual pieces with cotton or tissue to prevent breakage and damaged edges during shipment. Seal and mark the box containing them.

Hairs

(on moveable objects)

• Collect and protect the complete item.

(on fixed)

• Using tweezers, collect fibers and package

(control samples)

• Head: pluck 30-40 hairs from various areas
• Pubic: pluck 20-30 hairs
• Others: Pluck 10-20 hairs from areas of interest.
• Combed and plucked hairs are packaged separately

Insect: flies and maggots

• There are four stages in the life cycle of flies: eggs, maggots, pupae and adult
• The first insects that should be collected are the adult flies and beetles.  These insects are fast moving and can leave the crime scene rapidly once disturbed.  
• The adult flies can be trapped with an insect net available from most biological supply houses. 
• Once the adult flies have been netted, the closed end of the net (with the insects inside) can be placed in the mouth of a "killing jar" (which is a glass container with cottonballs or plaster soaked with ethyl acetate, or common fingernail polish remover). 
• The jar is then capped and the insects will be immobilized within a few minutes. 
• Once they are immobile they can be easily transferred to a vial of 75% ethyl alcohol.  
• Beetles can be collected with forceps or gloved fingers and placed directly into 75% ethyl alcohol.  
• The investigator should search for the presence of eggs, which are easily overlooked. 
• After this step, the larvae should be readily apparent on the body. Generally speaking, the largest larvae should be actively searched for and collected.   Additionally, a representative sample of 50-60 larvae should be collected from the maggot mass.  
• These insects can be placed directly into a killing solution or ethyl alcohol.  

Sources: http://www.crime-scene-investigator.net/evidenc3.html
http://www.crime-scene-investigator.net/collect.html#8 
http://www.forensicentomology.com/procedure.htm#scene
(2) Encyclopedia of Forensic Science
Picture sources: here, here