1. Importance
Blood is the most common, well-known and perhaps most important evidence in the world of criminal justice today. Without serologists, thousands of crimes may go unsolved due to bloods role in identifying suspects.
Blood evidence is found most often in "crimes of violence such as homicide, assault, and sexual assault."� It may be in the form of fresh liquid, coagulated, dried, or as a small drop or stain, and each form involves a different method of preservation and collection.

2. BLOODSTAIN PATTERNS
The angle of impact will help the investigator to determine where the victim was struck and at approximately what height.

3. BLOODSTAIN PATTERNS
The velocity of the blow can be determined by the size of blood droplets (Smaller= high velocity, Medium= medium velocity, Big= Low velocity).
The velocity also allows for the identification of the weapon used.

4. BLOODSTAIN PATTERNS
In the picture above, a serologist would be able to identify that the spatter we see is most likely coming from a dripping wound on the victim. We can draw this conclusion based off of the splatter around the drops. There is so little splatter in any direction that it was most likely dropped from above.
We can infer that this splatter stemmed from bullets due to the random placement and concentration of smaller droplets. The small amount of flow downwards allows the assumption that the cause was high velocity.

5. Importance
Blood spatter plays a huge role in serology by assisting in the identification of the murder weapon and the situation the victim may have been in.
Just from our few examples, we were able to identify not only the probable weapon, but also the position of the victim at the time of the attack. Some valuable information for detectives on a case.

6. Collecting Blood Dried Blood Stains
On clothing, if possible, wrap the item in clean paper, place the article in a brown paper bag or box and seal and label container. Do not attempt to remove stains from the cloth. On small solid objects, send the whole stained object to the Laboratory, after labeling and packaging. Do not mix dried stains. Place each stain in a separate envelope. Never attempt to wipe dried stains from an object using a moistened cloth or paper.
On large solid objects, cover the stained area with clean paper and seal the edges down with tape to prevent loss or contamination. If impractical to deliver the whole object to the Laboratory, scrape the stain onto a clean piece of paper, which can be folded and placed in an envelope. Do not scrape directly into evidence envelope. Scrape blood from objects using a freshly washed and dried knife or similar tool. Wash and dry the tool before each stain is scraped off. Seal and mark the envelope.

7. Liquid Blood Stains
Blood that is in liquid pools should be picked up on a gauze pad or other clean sterile cotton cloth and allowed to air dry thoroughly, at room temperature. It should be refrigerated or frozen as soon as possible and brought to the Laboratory as quickly as possible. Delays beyond 48 hours may make the samples useless.
If unable to deliver to the Laboratory, or if the object must be mailed, allow the stain to air dry completely before packaging.
Do not heat stained material or place it in bright sunlight to dry. Hang clothing and similar articles in a room where there is adequate ventilation.
If not completely dry, label and roll in paper or place in a brown paper bag or box and seal and label container. Place only one item in each container. Do not use plastic containers.

8. Storing Blood Stains and Controls Liquids (generally standards)
Air dry
Package in paper
Freeze
Consider special handling of non-absorbent items on (metal or plastic). Any condensation from thawing could disturb or destroy such evidence. Such items should be kept at room temperature and submitted to the lab as soon as possible.
Submit to the lab as soon as possible.
Liquids (generally standards)
Blood
Refrigerate, do not freeze standards collected in yellow stoppered vacutainers.
Submit to the lab as soon as possible.