Questions You May Find Useful in a Case that Involves Unidentified Latent Images

In this slide presentation are basic questions that should be asked when a case has latent images which haven’t been identified. The questions posed do not require a thorough knowledge of fingerprints and the search systems, they are basic questions which may prove beneficial in these type of cases.

Forensic Biometric Identification Solutions LLC.

What is an Unidentified Latent Image

These are latent finger or palm images that have the clarity and detail to be identified but

the donor remains unknown. In a criminal case these images have been compared with the

suspect and should have been compared with the victim(s). The latent images should’ve

been searched in the automated fingerprint search systems without returning an identification.

Depending on where the unknown latent images were discovered and recovered may have a

Significant impact on your case.

The Importance of Identifying any Unidentified Latent Images in a Case.

While everyone is aware of the importance of a latent identification, the absence of an

identification may be equally as crucial to your case. Since the unidentified latent images

have already been compared with the suspect and victim in the case, it’s in your clients best

interest to know the source of the unidentified images. Unfortunately these unidentified

latent images are not always accurately and thoroughly processed. If the latent's were

searched only once or the latent's were not entered into the unsolved latent file ; then the

possibility exists that the unknown latent images could be identified.

Latent Fingerprint Searches in Local, State and Federal Systems

Latent searches in an automated fingerprint search system are significantly less accurate than

arrest card searches and for that reason it may take more than one search to identify a latent

image. Latent system search accuracy can be as low as 50+ % accurate, this the reason that

experienced examiners will enter latent images a number times to insure an accurate search

Especially on high profile cases. Remember the latent image is unusually only a partial

impression (20% of an inked image) and often lacks image clarity which significantly

impacts the search system accuracy. If the latent image has only been searched once, there

is a possibility that the latent image may be identified if the latent images are resubmitted for

additional searches. You also want to insure all searchable unidentified latent images were

searched in the system.

When was the latent searched and has it been entered in the Unsolved Latent File

Most cases go to trial long after the initial investigation and you want to insure any

unknown latent images were entered into the unsolved latent file on the fingerprint search

system. This file searches new arrest cards against the unknown latent images stored in the

Unsolved Latent file. You want to insure that the unknown latent images for your case were

entered into the file and that any suspects generated by the file were evaluated by a latent

examiner. When agencies have a large backlog of work they may allow tenprint examiners

to check suspects or may in some cases not compare the suspects.

The Donor Print is Produced but is Missed by the Examiner

Another possibility is an error by an examiner. There are a number of reasons that a latent

search which may have produced a correct suspect was missed by the examiner; large

workload, poor training, *medical problem effecting the examiners visual acuity. Another

critical factor is unlike latent identifications when an examiner indicates a latent image is

not identified the image and suspects are not normally re-analyzed by another competent

latent fingerprint examiner.

*Note: The CDC has been estimated that in 2005 diabetes effected 14.6 million persons in the U.S. with an Additional 6.2 million undiagnosed individuals; very few agencies require vision examinations for employee's on a regular basis. One of the effects of diabetes is diabetic retinopathy causing blurry vision initially.

Latent Facts

Average size of a latent fingerprint fragment about 20% of a full fingerprint. containing between 15 and 35 minutiae (points of identification).

Typical inked fingerprint contains between 75 and 175 minutiae (points of identification).

latent images recovered from crime scenes are of poor clarity, increasing the likelihood of mistaking the type of minutiae being observed.

30% of crime scenes have usable latent images.

30% of the images from a crime scene are palm images.

20% of identifications at local lab's are now generated by the automated fingerprint search system.

Latent search accuracy can be as low as 54% on a large database, to mid 80% with good image clarity under controlled conditions.