Blood spatter (Abi)

Can various types of bloodstains be in one crime scene

Yes

what two forms can Gunshot spatter appear in

Forward or back

When can FORWARD spatter appear

When an exit wound exist

FORWARD spatter

Travels in the same direction as the direction of gun fire

BACK spatter

Travels in the opposite direction as the direction of gun fire.

When can Back spatter appear

Penetrating gunshot wounds

(For forward or back spatter) True or false: For both types there will be a pattern of droplets consistent with high velocity spatter

True

Gunshot wounds can do what

Penetrating (Enter) or Perforating (Exit)

What 3 factors influence the presence of BACK spatter

1) Location of injury

2) Size of wound

3) Muzzle to target distance

If an individual shoots themselves in the head, where would BACK spatter be located?

On their hand and/or arm.

What should you do when no BACK spatter was present on them when they shot themselves?

Question if it was a suicide.

Could BACK spatter appear on a perpetrator of a homicide?

Yes, if the muzzle to target distance is close enough

What indicates a contact gunshot wound?

Blood, tissue and hair in the bore or around a muzzle of a firearm.

What is biological evidence called that is found in the bore or around the muzzle of a firearm called?

Blowback

When does CAST-OFF spatter occur?

When blood flings off an object being used to commit a crime.

What needs to happen for CAST-OFF spatter to occur?

Blood must be shed first and then adhere to the object

What objects could create a CAST-OFF spatter

Knife, baseball bat and belt

Where to examine for the presence of CAST-OFF spatter

walls and ceilings

What is the pattern of CAST-OFF spatter

Arching

What influences the pattern of CAST-OFF

The weapon and amount of blood.

If CAST-OFF spatter is not present what has happened?

The object did not have a full swing or an intermediary object prevented the flight (such as the presence of clothing)

What can be determined by the CAST-OFF spatter pattern?

An estimated number of blows.

When is Arterial spurting/gushing created?

When a major artery is severed.

If the heart continues to pump out blood what does this do?

The blood is forced outside the wound producing a pattern.

Large volumes of blood will exit the wound, what else happens?

The pattern will resemble the heart beating and possibly have a flow pattern due to the quantity of blood.

Where is Expiratory spatter expelled from?

The nose or mouth

What happens due to the velocity of the blood being expelled?

Have similar characteristics of high - velocity spatter.

What can cause Expiratory spatter?

Internal injuries (blunt force trauma to the chest, gunshot wounds to the lungs) or natural disease (lung cancer)

What helps differentiating Expiratory spatter from other patterns?

Oxygen bubbles in the spatter pattern.

True or false: the presence of blood is just as important as its absence.

True

When does VOIDS occur?

When an object prevents blood being deposited on a surface.

What do VOIDS create?

A blank space

What do VOIDS assist in?

Reconstructing a crime scene, identifying the size and shape of an object or the size of person.

How do you create a TRANSFER pattern

Bloody objects placed on a surface containing no blood

What objects can create a transfer pattern?

Fingerprints, footprints, footwear impressions and weapons

True or false: the transfer pattern will create an image similar to the object depositing the blood on the surface.

True

What are flow patterns?

The movement of blood due to the forces of gravity.

What causes the flow pattern to be small or large

Depending on the source of the blood.

True or False: active flow patterns come from an actively bleeding wound.

True

When can passive flow patterns occur?

After blood has already been deposited and flows as a result of gravity. (Seen in cases of arterial spurting/gushing patterns)

What is a large accumulation blood known as

A pool

When will a pool of blood occur?

On a level surface

True or false: when a pool occurs in an absorbent material (furniture or carpet) the pool will become larger then the original pool.

True

What is it called when the edges of a bloodstain drys on a surface?

Skeletonization

What happens if the criminal attempts to wipe clean the bloodstain?

The edges of the bloodstain will remain intact.

What does the presence of Skeletonization provide?

A timeline of when blood was initially deposited

When are Trail patterns formed?

From blood dripping from an injury or a weapon and provides a path of movement.

What is velocity of trail patterns

Low

(This is about Trail patterns) True or false: the movement of the subjects may create tails and thus show directionality

True

What are Swipe patterns?

A transfer of blood from a moving object to an untrained surface

How are swipe patterns direction determined ?

Based on the pattern

When do wipe patterns occur?

When an object moves through an existing bloodstain resulting in the removal or alteration of its appearance.

Why is documenting bloodstain evidence important?

To help reconstruct a crime scene

What does photographic documentation aid

In determining the angle of impact and the direction of travel.

Where will bloodstained evidence be present

In the general crime scene photographs

True of false: photographs should also be taken that focus solely on bloodstains

True

How do you take photographs of bloodstains

Overall, mid range and up close photographs, this will show the entire pattern

What object should you use in photos of additional close ups of individual patterns

A ruler

What does the ruler do?

Frame the pattern to provide sense of the overall size.

What is the name of the method that uses rulers in photos

Perimeter ruler method

What else should be placed next to bloodstains other than a ruler?

Numbered evidence stickers

How is the photographic documentation of the bloodstain pattern completed?

In a unaltered state and after the labelling of the pattern

What is another method used to document bloodstains other than the ‘perimeter ruler method’?

Grid method

What is the grid method

A grid created using tape to map the blood stains

What photos are taken when using the grid method?

Overall, midrange and close ups are taken of the bloodstain with and without the grid.

True or false: the documentation of the bloodstain stain patterns should be in the investigative notes and in the scene sketches

True

What types of scene sketch’s do you use for blood stains

Exploded scene sketch and a more detailed version, a blow up sketch.

To ensure a substance is blood what test can be taken?

A presumptive test

What do you use for a presumptive test?

Phenolphthalein

What is the steps when taking a presumptive test using phenolphthalein

The phenolphthalein is placed on a swab and then the substance is swabbed.

What is the reaction to a presumptive test using phenolphthalein if the substance is blood?

If positive the swab will turn pink once the substance is swabbed because the chemicals react with the heme molecule that is present in blood.

What is luminol used for at a crime scene.

luminol Is used to detect blood that can not be seen. (Normally if the criminal has cleaned the crime scene)

How does luminol work

The room has to be dark.

The luminol is sprayed onto the surfaces and if there is blood a blue chemiluminescence will appear on the substance. The blue chemiluminescence will only last for 30 seconds.

Why does luminol react to blood like that?

Because Luminol is a sensitive reagent that oxidizes by hydrogen peroxide in alkaline solution in the presence of the heme molecule in the blood.

True or false: Luminol has been found not to interfere with future DNA test on the blood.

True