CLPEX Chat Board

Good Morning!

I have searched the message board archives for answers to this question without success.

I am preparing a fingerprint chart for court. The latent was photographed 'in situ' on the magazine of a gun. It was not 'lifted'. (I don't know why, but I will find out before I get in the witness stand.)

The digital image was searched on AFIS and an identification was made. It is now up to me to present this evidence in court.

What kinds of challenges can I expect from the defense regarding the digital-only image of the latent? (Besides manipulation of a digital image, that is!).

I think the short answer is "similar to those challenges encountered for traditional photography'.

I'm not specifically familar with laws and admissability rules in your jurisdiction, however the classic question is generally along the lines of "Is the image a true and accurate representation the the actual item/scene depicted?" This should apply to virtually any image offered as evidence, whether through traditional or digital photography, or acguired via a copy machine or digital scanning.

'Best evidence' rules may apply... Is the original item (gun magazine) available? Is the latent print still visible on the item? If so, authentication of the image may be self evident (assuming no anomalies). If not, the authentication may rest with the testimony, documentation and credibility of the person(s) doing the processing/photography. Are there other photographs/images of the magazine showing relative position on the latent print on the magazine?

Is there an equivalent of a film negative for establishing original image? Typically a digital image file will be recorded on a memory card, and then downloaded to a computer storage device for archiving, often a CD or DVD. As long as there is documentation of a direct transfer with no changes, and the storage medium is locked, preventing subsequent change, that file may be accepted as the original image.

File format may be called in to question... is the image from a lossless (i.e. RAW or TIF) or lossy (i.e. JPG) file format? Some knowledge of possible resolution issues (i.e. visible pixelation at the enlargement level needed for comparison) may be helpful.

Regards, RLT

It turns out that the latent on the magazine was developed by glue fuming, which is why it wasn't "lifted". The Officer in Charge of the case will have the weapon in court. I have the photo technician on 'stand-by' to answer the technical questions about digital photography. Life is good.

Thanks to all of you for your input.