In forensic investigations, law enforcement rely on trace evidence including blood, urine, and body fluid stains to support individuals accounts of the events and determine whether a particular suspect or victim was involved. The evidence also includes nonbiological residues such as pepper spray self-defense weaponry by the general public, criminals, and law enforcement. This investigation examined the effects of storage and washing detection of pepper spray residues (i.e., capsaicinoids on cotton, cotton-polyester blend, wool and nylon fabrics). Several scenarios were created where storage, time, and garment treatment may be factors in the detection of capsaicinoid residues: 1) the victim of an assault used pepper spray in self-defense and the assailant washed and discarded the clothing, which was discovered weeks after the attack; 2) a person was involved in a civil disturbance where pepper spray use resulted in accidental exposure. The person’s clothing may provide evidence of exposure; and 3) a suspect was sprayed by a law enforcement agent, but not apprehended. The suspect discarded or washed the clothing prior to apprehension. The findings showed that the concentrations of capsaicinoid analogues on fabrics decreased between 5 percent to 60 percent during the 6 months of storage when compared with samples of each fabric type that were prepared and analyzed at the onset of the stability study. The rate of disappearance of the capsaicinoid was analogue specific. Degradation of the capsaicinoid was independent of the fabric type and the temperature of storage. Also investigated was the effect of washing the fabrics on the detection of capsaicinoids. Fabrics were washed in water, 1 percent detergent, 1 percent bleach, or 5 percent Spray and Wash. Water was the least effective method of removing the capsaicinoid from the fabrics and bleach the most effective. Retention of the capsaicinoid on the fabrics following washing was affected by fabric type and the chemical properties of the individual capsaicinoid analogues. 36 References