Crj 311 Forensics: Individualized Patterns Of Evidence
Impression Evidence
CRJ 311 Forensics
Instructor Myron Gilbert
May 25, 2014
Impressions Patterns for individualization are characteristics that can be unique among the members of their class. This means that we could possible match a tire mark to a particular tire or a shoe print to a sole this could prove invaluable to investigators. Reviewing the evidence pictures both would by considered impressions they have both left imprints in the soil. I will discuss the type of individualized patterns of both pictures and how one would preserve this type of evidence. Lastly, what type of information can be collected from these types of evidence. The first evidence picture is a tire mark. From this picture you can
see that it is marked with a ruler for length and width and an evidence marker number has been given. This would be an example of a positive impression. The second evidence picture is a negative impression of a shoe in soft soil. It also has been recorded with a scale to show length and width. Both pieces of evidence show good contrast obviously the shoe print is the better of the two. Casting will have to be done on both in the form of dental stone as it provides the best option for capturing the details. Once the plaster is completely hardened it can be compared two the tire or footwear. “Both in collecting evidence and in thinking about how pattern comparisons are done, it is important to remember that comparisons must be made between like impressions. Left with left, right with right, positive with positive, and negative with negative (Gaensslen & Larsen, 2013). Examiners will have to create a known sample of the tire and shoe impressions the type size and make. One thing with the shoe print there has to be a mirrored image that has to inked on paper since positive and negative impressions cannot be compared. The tire pattern looks to be a regular road tire approximately 12 inches in width looks like a common tire. The shoe looks to be 280mm, which is around a size 11 and has some sort of marking in its center. It also looks like a cross-trainer or lite work boot. Packaging both pieces of evidence in the plaster molds
The item bearing the print or the tape lift must be carefully packaged, labeled, and sealed. Items have to be packaged so as to provide maximum protection of an undeveloped print impression. Nothing should touch or rub the impression during storage or transport. Some type of wood or plastic trough would have to be used to protect the ridge impressions from the package during transport (Gaensslen & Larsen, 2013).
Physical matching is done by the eye, or with the aid of a magnifier or stereo microscope. This is a microscope with two eyepieces (enabling stereo vision) that is essentially a magnifier. This type of matching is intuitive and quite familiar to people. As a result, it is very convincing for a jury or judge, because they can look at it and see it for themselves. Forensic examiners could learn many things from these two impressions. First the tire impression you could get the tire type and make. This information could lead to production vehicles that have this type. If it is an exotic type of tire then it could be narrowed down to suppliers or specialty automotive companies. The shoe analysis would probably be the toughest to distinguish since it has to be compared to hundreds of shoe patterns. If the center marking can be identified to a particular manufacturer than it could be easier to locate the model of shoe. If both pieces of evidence were to be identified it would only tell what type of shoe or type of tire. Not who was driving or wearing the shoe if it were to be matched to a suspect’s tire or car then this would add to evidence against the suspect.
References
Gaensslen, R.E., & Larsen, K. (2013). Introductory forensic science. San Diego, CA: Bridgepoint Education, Inc.
CRJ 311 Forensics
Instructor Myron Gilbert
May 25, 2014
Impressions Patterns for individualization are characteristics that can be unique among the members of their class. This means that we could possible match a tire mark to a particular tire or a shoe print to a sole this could prove invaluable to investigators. Reviewing the evidence pictures both would by considered impressions they have both left imprints in the soil. I will discuss the type of individualized patterns of both pictures and how one would preserve this type of evidence. Lastly, what type of information can be collected from these types of evidence. The first evidence picture is a tire mark. From this picture you can
see that it is marked with a ruler for length and width and an evidence marker number has been given. This would be an example of a positive impression. The second evidence picture is a negative impression of a shoe in soft soil. It also has been recorded with a scale to show length and width. Both pieces of evidence show good contrast obviously the shoe print is the better of the two. Casting will have to be done on both in the form of dental stone as it provides the best option for capturing the details. Once the plaster is completely hardened it can be compared two the tire or footwear. “Both in collecting evidence and in thinking about how pattern comparisons are done, it is important to remember that comparisons must be made between like impressions. Left with left, right with right, positive with positive, and negative with negative (Gaensslen & Larsen, 2013). Examiners will have to create a known sample of the tire and shoe impressions the type size and make. One thing with the shoe print there has to be a mirrored image that has to inked on paper since positive and negative impressions cannot be compared. The tire pattern looks to be a regular road tire approximately 12 inches in width looks like a common tire. The shoe looks to be 280mm, which is around a size 11 and has some sort of marking in its center. It also looks like a cross-trainer or lite work boot. Packaging both pieces of evidence in the plaster molds
The item bearing the print or the tape lift must be carefully packaged, labeled, and sealed. Items have to be packaged so as to provide maximum protection of an undeveloped print impression. Nothing should touch or rub the impression during storage or transport. Some type of wood or plastic trough would have to be used to protect the ridge impressions from the package during transport (Gaensslen & Larsen, 2013).
Physical matching is done by the eye, or with the aid of a magnifier or stereo microscope. This is a microscope with two eyepieces (enabling stereo vision) that is essentially a magnifier. This type of matching is intuitive and quite familiar to people. As a result, it is very convincing for a jury or judge, because they can look at it and see it for themselves. Forensic examiners could learn many things from these two impressions. First the tire impression you could get the tire type and make. This information could lead to production vehicles that have this type. If it is an exotic type of tire then it could be narrowed down to suppliers or specialty automotive companies. The shoe analysis would probably be the toughest to distinguish since it has to be compared to hundreds of shoe patterns. If the center marking can be identified to a particular manufacturer than it could be easier to locate the model of shoe. If both pieces of evidence were to be identified it would only tell what type of shoe or type of tire. Not who was driving or wearing the shoe if it were to be matched to a suspect’s tire or car then this would add to evidence against the suspect.
References
Gaensslen, R.E., & Larsen, K. (2013). Introductory forensic science. San Diego, CA: Bridgepoint Education, Inc.