The use of a drug to modify a person's behavior for criminal gain is not a recent phenomenon. However, the recent increase in reports of drug-facilitated crimes (sexual assault, robbery) has caused some alarm in the general public. Drugs involved can be pharmaceuticals such as benzodiazepines (flunitrazepam, lorazepam, clonazepam), hypnotics (zopiclone, zolpidem), sedatives (neuroleptics, some antihistamines), or anesthetics (GHB, ketamine); drugs of abuse such as cannabis, ecstasy, or LSD; or, more often, ethanol. Mistreatment of older people, whether it is abuse or neglect, can be classified as physical, psychologic, or financial/material. Several types of mistreatment may occur simultaneously. Very few data are available in the international literature. It seems that mental abuse and neglect are more frequent, but physical abuse such as beating, pushing, kicking, and possibly sexual abuse have also been reported. Drugs used to facilitate sexual assaults can be difficult to detect (active products at low dosages, chemical instability), can possess amnesic properties, and can be rapidly cleared from the body (short half-life). In these situations, blood, or even urine, can be inadequate. This is the reason why some laboratories have developed an original approach based on hair testing. Hair was suggested as a valuable specimen in situations in which, as a result of a delay in reporting the crime, natural processes have eliminated the drug from typical biologic specimens. Hair analysis may be a useful adjunct to conventional drug testing in sexual assault. It should not be considered as an alternative to blood and urine analyses, but as a complement. Mass spectrometry/mass spectrometry technologies appear to be required for analyses in drug-facilitated cases. The experience of the authors is presented in cases involving the elderly and chemical poisoning.