NCJ Number
220052
Journal
Law Enforcement Technology Volume: 34 Issue: 8 Dated: August 2007 Pages: 118,120,125
Date Published
August 2007
Length
7 pages
Annotation
This article describes how LACE (Law Enforcement Against Child Exploitation) software, which is in the final stages of development by BlueBear, Inc. (Gatineau, Quebec), can assist investigators in sorting and categorizing images found on seized computer hard drives in child exploitation/pornography cases.
Abstract
The article describes how one investigator, Detective Constable Phil Shrewsbury-Gee of the York Regional Police (Ontario, Canada), uses LACE in organizing computer images in child pornography cases. The first software program Shrewsbury-Gee had used to compare computer images of child pornography compared the hash value of files (a series of numbers used to authenticate electronic file transmission). The challenge in looking at hash values is that any change results in a hash value change. Shrewsbury-Gee was frustrated because one image saved as a JPEG, TIFF, GIF, and bitmap would be identified as four unique images. Using the hash value to compare images reduces an investigator's workload by less than half. Image marks (a string of numbers) used in LACE further reduce an investigator's workload by finding more matches to previously categorized images. Image marks are similar to file hash, but are more tolerant of variations. LACE parallels the ability of humans to determine the similarities between pictures while using computer power to manage massive amounts of child pornography, according to Shrewsbury-Gee. Still, every computer hard drive will have some unique images, perhaps family photographs or pornographic pictures taken by a suspect that haven't yet been shared. They must be manually categorized. Police who use LACE spend less time but do a better job in organizing evidence and bringing more cases to trial with less effort.