The crime of arson is rather singular in nature as to the physical evidence usually found during investigation. The physical evidence at the scene is often destroyed by the fire, but not always. Any detected materials related to the crime can often speak very strikingly and forcefully with the aid of laboratory studies thereon. As a review of the field of evidence in law, we meet the classification of (1) testimonial evidence and (2) physical evidence. Under the first class fall those statements of witnesses and suspects, which may or may not be reduced to writing. The second class, namely, physical evidence refers to those material things we can see, feel, smell, and taste. Fuels, containers, metal parts of an incendiary contraption, partially burned wood, tire tracks, etc., are examples of physical evidence the arson investigator may encoutner. The witness may be examined and cross examined to test his accuracy and veracity at the trial. Physical evidence can speak rather fluently and convincingly for itself if it is competently handledfrom scene to trial. Technical findings obtained by processing of this evidence are presented as expert testimony, and therefore as advisory aid to the court and jury at the trial. In all criminal cases including arson, the law requires careful scrutiny of the evidence offered in order to safeguard the rights of the defendant. This is to make certain that it is competent, and sheds some light on the question at bar, namely, the guilt or innocence of the defendant. These safeguards are not tricks, nor red tape, nor stumbling blocks for the prosecution, but safeguards that you, too, as a defendant would want to see observed. You, as a defendant, would certainly want to see negligence, gross carelessness, and possibility of fraud ruled out when some object was introduced against you as evidence at your trial. The law requires such safeguards for all defendants by requiring that certain basic rules must be met. These may be summarily listed as follows: 1. Is the object related to the crime? 2. Was its authenticity and competence maintained from scene to trial? 3. Was it competently examined? 4. Are the results competently and properly presented and interpreted? Three general points arise in connection with admitting into evidence any laboratory findings made on objects secured during the investigation: 1. Admissibility of the object.