I have done some research, and most likely there would not be much stated regarding the knife in a case where the murder weapon was not at the scene of the crime.
KNIVES Knives are close-combat weapons. Unlike firearms, which allow you to murder at a distance, knives involve direct contact between the victim and the assailant. Because of this, a man usually stabs another man, or a woman. It's very rare for a woman to stab a man, even in crimes of passion, because it's much too easy for a larger, stronger male to overcome his smaller, weaker assailant. Most crimes of passion involve a man killing a woman with whatever weapon happens to be within reach, a kitchen knife, a fireplace poker, a heavy vase, or any number of other blunt objects. When a woman kills a man in a crime of passion, it's most often with a gun, his own if it's available. Women tend to see a kind of justice in killing a man with his own weapon.
As with gunshot wounds, there are several factors to be taken into consideration when determining if a death is homicide or suicide.
- Defensive cuts: In a homicide, there will be defensive cuts on the palms of the victim's hands and on the underside of her arms as she tries to fight off her attacker.
- Number of wounds and their location: A murder usually involves multiple stab wounds to the side, back or stomach. In a suicide, while there may be additional cuts across the wrist and tentative test stabbings to see if it will hurt, or to work up courage, there will usually only be one wound and most likely in the chest.
- Location of the murder weapon: In a suicide, the weapon will be at the scene with the victim's fingerprints on it. In a homicide, the weapon is often missing.
- Presence of a note: A suicide victim will almost always leave a note.
- Stabbing through clothing: A suicide victim will rarely stab herself through her clothing, instead she will open her shirt to expose the skin. Stabbing through clothing, even if there's only one wound, may indicate homicide.
I further found on Forensic Evidence.com information regarding knives and determinations:
http://www.forensic-evidence.com/site/ID/toolmark_id.html
WARNING: GRAPHIC
III. KNIFE MARK EVIDENCE
Traditional "knife mark" evidence is a subgroup of the broad category of evidence commonly referred to as "tool mark" evidence. The theory underlying tool mark evidence, which is explained below, is generally accepted in the scientific community and has long been upheld by courts. Many of the analytical methods that were developed for use with tool marks in general have been applied to knife marks in particular and have similarly been accepted by courts. Hart's theory of knife mark identification, however, departs from traditional knife mark identification theory in significant ways, and the State has cited no appellate decision upholding his theory.3
A.
Traditional Knife Mark Evidence
The term "tool mark" refers to the mark left by a hard material when striking a softer material, and such a mark generally falls into one of two classes, i.e., (1) an impression marking, or (2) a striation marking:
A toolmark may be described briefly as the mark left by an instrument or an object composed of a hard substance coming in contact with and leaving some characteristic mark or impression on a relatively softer medium.
Toolmarks may show one of two things: (1) a negative reproduction of the tool itself--size, shape, and contour--which is a true impression; (2) a series of parallel striations [or lines] caused by dragging the tool across the surface of the softer medium.
The basic principle in toolmark comparison is the reproduction of similar marks with the suspected tool or instrument, simulating as nearly as possible the conditions under which the original marks were made. Leland V. Jones, Locating and Preserving Evidence in Criminal Cases, in 1 Am.Jur. Trials 555, 616 (1964).
An identification procedure commonly used by tool mark experts is as follows: (1) the expert attempts to duplicate the original crime-scene mark by using the suspected tool to create a comparable mark on a similar test medium; (2) the test mark (i.e., the "exemplar") is compared to the original mark via microscopic examination; (3) patterns of impressions or groups of striations are matched up under a three-dimensional stereoscopic comparison microscope; (4) two dimensional photomicrographs (i.e., photos) of the comparison are taken for record purposes; and (5) if the marks are sufficiently similar, the expert may conclude that they were made by the same tool (i.e., the suspected tool). Marks left by various tools have been studied in this manner, including screwdrivers, chisels, wire-cutters, hammers, axes, and knives.
Unlike wood, metal, plastic, and other hard surfaces, human tissue is pliable and does not readily retain detailed marks. Thus, knife mark analysis in human tissue traditionally has been limited to a gross observation of the wound itself and a microscopic examination of the interior and exterior surfaces of the wound to detect alterations in the cellular structure of the tissue or the presence of fibers or other trace materials. From this analysis, an examiner may deduce, for instance, the general length, width, shape, or contour of the knife blade, and the presence of any foreign matter.
Specifically, courts have permitted experts to attest to the following: that a particular knife could have been the murder weapon; that a particular knife was consistent with the victim's wounds; that a victim's wounds were caused either by a particular knife or a knife similar thereto; and that a victim's wounds could not have been caused by a particular knife. On the other hand, courts have approached with caution an expert's testimony that a victim's wounds were caused by a particular knife.
