Case (cite)
People v. Fisher, 172 N.E. 743 (Ill. 1930)
“In Lyon v. Oliver, 316 Ill. 292, 147 N. E. 251, it was pointed out that handwriting, photography of questioned documents, and identification of typewriting were subjects for expert testimony. It was in that case shown that the same typewriter might, after considerable use, register letters of different form from that which it would make of the same letter when the machine was new, and that whether this has occurred in any given case is a subject for expert testimony. We are of the opinion that in this case, where the witness has been able to testify that by the use of magnifying instruments *241 and by reason of his experience and study he has been able to determine the condition of a certain exhibit, which condition he details to the jury, such evidence, while the jury are not bound to accept his conclusions as true, is competent expert testimony on a subject properly one for expert knowledge.”
Objection is made to the admission of the testimony of Goddard that he was able to tell by the shotgun shells found, and the sawed-off shotgun offered in evidence, that the shells were fired by that gun. He explained that under a microscope the imprint of the firing pain of the shotgun is evidence was unmistakably shown on the caps of the discharged shells found in the automobile. He explained that no two firing pins make exactly the same impression, but that the small rings made in turning out the point of the firing pin are shown under the microscope to vary in each instance, and that the rings formed in the imprint on the cap of the shells fired in this case were identical with the rings shown under the microscope on the firing pins of the shotgun in evidence. Such evidence was competent for what it was worth.