Fingerprint Examinations Flashcards

1
Q

Can you explain what the brush and powder method is and how it is used?

A

Brush and powder is a method for developing fingerprints, most often used at crime scenes.

The powder is applied to a feathered brush, and then lightly dusted over the surface being examined for fingerprints. The powder attaches to the fingerprint residue, therefore increasing the contrast between the fingerprint and its background.

This makes it easier to locate and preserve fingerprints at the crime scene.

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2
Q

What are fingerprint lifts?

A

Fingerprint lifts are square sheets of gelatine, with one side that is slightly tacky. When placed on a surface that has been dusted for fingerprints, the powder which has attached itself to the fingerprint is lifted from the surface by the gelatine.

The fingerprint lift is then placed tacky-side down on a square acetate sheet, along with a signed and dated label, which includes a unique identifier and a description of where the fingerprint was located.

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2
Q

The brush and powder method sounds like an abrasive method - how do you avoid damaging the fingerprint?

A

Fingerprints are fragile, and therefore surfaces are dusted for fingerprints using a circular motion, ensuring that only the very ends of the feathers make contact with the surface. This ensures that powder is applied to the surface without damaging the fingerprint.

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3
Q

Why were some of the exhibits examined at the scene, and others in the laboratory?

A

When we locate items at a crime scene, we make a judgement call as to whether that item would be better examined at the crime scene, or in the fingerprint lab where we have a greater number of treatments available to us.

This judgement is based on whether it is practical to remove and transport that item to the lab, and whether the results that we would achieve in the lab would likely be better than what can be achieved at the crime scene.

It is my opinion that examining the seized items in the lab would produce better results than what could be achieved at the crime scene, which is why they were removed from the vehicle for later examination in the lab.

I decided to examine the mobile phone at the scene as many of the treatments that are available in the fingerprint lab would compromise other types of forensic evidence, including the digital information held on the mobile phone. I therefore made the decision to use sterile brush and powder to examine the phone at the scene so that the other types of forensic evidence would be preserved.

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4
Q

What is superglue fuming, and how is this process used?

A

Superglue fuming is a method for developing fingerprints commonly used in the laboratory.

To superglue an item, the item is placed into a sealed chamber along with a small amount of superglue. When heated, the glue forms a vapour that fills the chamber.

Fingerprints attract the vapour which gradually forms a white layer of hardened glue. This layer not only makes the fingerprint more visible but also slightly more durable.

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5
Q

What is panacryl?

A

Panacryl is a dye stain that we use for enhancing fingerprints that have been developed using superglue fuming.

Fingerprints that have been treated with panacryl can be further enhanced using a forensic light source.

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6
Q

What is wet wop?

A

Wet wop is a method for developing fingerprints on sticky surfaces, such as tape.

The wet wop solution is made of powder suspended in detergent, which is applied to an item with a paintbrush, and then washed with water. The suspended powder adheres to the fingerprint and washes from the rest of the surface, forming a visible fingerprint that can be photographed.

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7
Q

Are there other methods you could have used to develop fingerprints on this surface?

A

We have a range of methods available to us for developing fingerprints, and how we select a particular method depends on the constituents of the fingerprint, as well as the characteristics of the surface on which the fingerprint is deposited.

Based on my knowledge, training, and experience, the method that I selected was most appropriate for developing fingerprints on this type of surface.

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8
Q

What is RTX?

A

RTX, or ruthenium tetroxide, is a fuming method for developing latent fingerprints.

When examining an area for fingerprints with RTX, we use a handheld fumer, which vaporizes the RTX solution and produces a fume that can be directed toward a certain area with a small hose.

The RTX reacts with any fingerprints and turns them dark brown, therefore increasing the contrast between the fingerprint and the background surface, and making it easier to locate and preserve any fingerprints.

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9
Q

What measures were put in place to protect the integrity of the scene?

A

Throughout my examination of the vehicle, I wore full personal protective equipment to avoid contaminating the vehicle with my own fingerprints and DNA. This included a disposable suit, gloves, hair net, and mask.

Prior to beginning my examination, I had a discussion with members of ESR to determine what areas they would be interested in sampling for DNA. These areas, which included the interior door handles, were examined with a sterile brush and powder so that any fingerprints on these areas could be located and preserved before being sampled for DNA.

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10
Q

How do we know that the fingerprints you identified were the same fingerprints that were located at the scene?

A

I took photographs showing the location of all fingerprint lifts in situ prior to removing them from the vehicle. Each of these lifts were assigned a unique identifier which is visible in these photos, and once removed from the vehicle, these fingerprint lifts were given a signed and dated label that described the location of the fingerprint.

Following my examination of the vehicle, I hand-delivered all fingerprint lifts to the South Island Forensic Fingerprint Section for further examination.

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11
Q

Why did you examine these areas of the vehicle and not others?

A

Based on the information that I received about the offence prior to attending the scene, as well as discussions that I had with the Officer in Charge of the scene, I focused my examination on areas that were relevant given the circumstances of the offence.

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12
Q

Were any items seized from the vehicle?

A

Three items were seized from the vehicle, including a piece of brown tape from the rear passenger’s-side seat, a McDonalds cup from the front passenger’s seat, and a magazine clipping from the rear driver’s-side seat.

These items were photographed in situ before being removed from the vehicle and packaged.

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13
Q

What methods did you use to locate and develop fingerprints on the piece of tape?

A

I first used a forensic light source to examine the tape for fingerprints. Fingerprints were located but I was unable to successfully photograph them due to a lack of contrast between the fingerprint and the background surface.

The tape was then superglue fumed, and again visually examined with the forensic light source. The fingerprints that I had initially located appeared to be enhanced by the supergluing process. I labelled these fingerprints ‘A’, and preserved them with photography.

I then used panacryl to treat the non-sticky-side of the tape for fingerprints, and wet wop to treat the sticky-side of the tape for fingerprints. As a result of these treatments, I located two further fingerprints: one on the sticky-side of the tape, which I labelled ‘B’, and one on the non-sticky side, which I labelled ‘C’. Both fingerprints were preserved with photography.

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14
Q

What is the DCS5?

A

The DCS5 is a system that combines photography with specially designed computer software that assists us in locating and preserving fingerprints in the fingerprint lab.

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15
Q

What is a forensic light source?

A

A forensic light source is a specialised torch which is used to assist us in locating and preserving fingerprints both at the crime scene and in the fingerprint laboratory. The forensic light source emits high-intensity light in a range of different colours of light, and the specific colour of light used depends on the residue of the fingerprint, or the chemical used to enhance the fingerprint.

For example, we often use a chemical called panacryl, which is a dye stain that can be used for enhancing fingerprints. We can further enhance fingerprints developed using panacryl with a forensic light source emitting blue light.

16
Q

On what side of the tape were fingerprints ‘A’ to ‘C’ located?

A

Fingerprints labelled ‘A’ and ‘C’ were located on the non-sticky side of the tape, and fingerprint labelled ‘B’ was located on the sticky side.

17
Q

Did you discuss examination strategies with other forensic specialists present at the scene?

A

Before commencing my examination, I had a discussion with the Officer in Charge of the scene as well as a member of ESR where we discussed what areas would serve as the target areas of our examination, as well as the order in which we would carry out our examination so that all available forensic evidence could be preserved from the scene.

This discussion was ongoing throughout the examination.

18
Q

What is a re-lift?

A

Often when we lift a fingerprint following the use of brush and powder, fingerprint residue will remain on the surface. We can use a second fingerprint lift to ‘re-lift’ the fingerprint or apply more powder to the fingerprint and re-lift it. These additional fingerprint lifts are known as re-lifts.

19
Q

Are there any manuals or guidelines that you can refer to when deciding what treatments to use to develop fingerprints on particular surfaces?

A

Our decision-making surrounding treatment selection is guided by the Home Office Manual, which describes the most effective methods for locating and developing fingerprints in various residue types on various surface types.

This manual is constantly revised to reflect current research.

20
Q

Is there a chance that you could have developed more fingerprints if you had used different treatments?

A

There is a chance; however, based on my knowledge training, and experience, the methods that I used were the most appropriate for developing fingerprints on this particular type of surface.

21
Q

How did you approach removing and packaging the items from the vehicle?

A

Before removing the items from the vehicle, I advised the Officer in Charge of the scene on appropriate packaging methods and took photographs showing the location of the items in situ.

Then, wearing personal protective equipment, I removed the items from the vehicle and placed them in packaging, which was then sealed and labelled.

22
Q

Where were the fingerprints lifts and exhibits stored back at the SIFFS?

A

The fingerprint lifts and exhibits were stored in a secure location in the South Island Forensic Fingerprint Section, which is an area that can only be accessed by police members.

23
Q

Why are the fingerprint photographs different colours?

A

These fingerprint photographs were captured with the assistance of the forensic light source, which as I have mentioned can emit light in a variety of colours to enhance fingerprints.

The specific colour used to enhance the fingerprint depends on the treatment that has been used to enhance the fingerprint. For example, fingerprints that have been treated with panacryl often appear green in photographs of the combination of the blue light and yellow camera filters that are used to enhance and visualise the fingerprint.

24
Q

Why did you photograph fingerprint AA01 and preserve the remainder with fingerprint lifts?

A

Fingerprint AA01 was a patent fingerprint, meaning that it was visible to the naked eye without some method being used to enhance the fingerprint. Typically, photography is used to preserve patent fingerprints.

The remaining fingerprints on the other hand were latent fingerprints and I therefore used brush and powder to visualise them. Fingerprint lifts are common and reliable means of preserving fingerprints that have been developed with brush and powder.

25
Q

Why did you use RTX?

A

I used RTX as a means of treating the area surrounding fingerprint labelled ‘AA01’ for fingerprints before attaching a label to the surface of the vehicle. This ensured that the label wasn’t placed on top of any latent fingerprints.

26
Q

Why didn’t you photograph the remaining fingerprints at the scene before lifting them?

A

As the surface on which the fingerprints were located appeared to be clean and smooth, I was confident that the fingerprints would be well preserved by the fingerprint lifts.

If I was not confident of this then I would have photographed them first.

27
Q

When you examine a scene, how do you know where/what to examine?

A

Prior to beginning my examination of a scene, I develop an examination plan of what areas to examine, and how I will examine them. This plan is based on the information I received about the alleged event prior to attending the scene, as well as on discussions that I have with the Officer in Charge of the Scene prior to beginning my examination.

This examination plan takes into account the circumstances of the alleged event and where the event took place, as well as the suitability of any relevant surfaces for locating, developing and preserving fingerprints.

28
Q

How do you maintain custody of any preserved evidence?

A

When evidence is preserved from a crime scene, I record the time and date that I preserved the evidence. When I hand the evidence to another police member, again this information is documented along with who the item was handed to.

This information is known as an item’s chain of custody, which serves as a log for who has been in possession of an item, and when they were in possession of it.

29
Q

What measures do you take to ensure the integrity of evidence in the lab?

A

Prior to beginning my examination of these items in the fingerprint lab, I made sure I was wearing the appropriate personal protective equipment, which in this case included gloves and a mask.

Throughout my examination I communicated with a member of ESR, to ensure that these items were examined in a sequence that ensured that all available forensic evidence was collected from the items.

30
Q

Is it possible that someone may have touched the vehicle while it was being stored at the tow yard?

A

The OTS Tow Yard, which is where the vehicle was stored and examined, is a secure facility, which cannot be accessed by the general public without authorization.

Therefore, it would not be possible for an unauthorized member of the public to enter the facility and touch the vehicle while it was being stored there.