Method of identifying a thief and stolen articles

A method of identifying an article at least a portion of which has been contacted with an effective amount of a first material selected from the group consisting of ninhydrin and hydrindantin and mixtures thereof comprising contacting said article with a second material selected from the group consisting of amino acids, ammonia, ammonium salts and primary and secondary organic amines and mixtures thereof, thereby causing a colored reaction product to be formed on the portion of said article having been contacted with said first material.

A method of chemically labeling an article with an imperceptible latent color reagent and subsequently identifying said article from other articles not so labeled comprising:

• first contacting at least a portion of said article with an effective amount of a first material selected from the group consisting of ninhydrin and hydrindantin and mixtures thereof, thereby labeling said article;
• and,
• subsequently contacting said article with an effective amount of a second material selected from the group consisting of amino acids, ammonia, ammonium salts and primary and secondary organic amines and mixtures thereof, thereby causing a colored reaction product to form on the portion of said article first contacted with said material.

A method of identifying a stolen article comprising:

• contacting at least a portion of said article prior to its theft with an effective amount of a first material selected from the group consisting of ninhydrin and hydrindantin and mixtures thereof, thereby chemically labeling said article with an imperceptible amount of a latent color reagent;
• and,
• contacting said article with an effective amount of a second material selected from the group consisting of amino acids, ammonia, ammonium salts and primary and secondary organic amines and mixtures thereof after the theft of said article, thereby causing a colored reaction product to form on the surface of the portion of said article contacted with said first material.

A method of chemically labeling a person comprising contacting the skin of said person with an effective amount of a latent color reagent selected from the group consisting of ninhydrin and hydrindantin and mixtures thereof.

A method of chemically labeling a person comprising:

• first contacting at least a portion of an article with an effective amount of a latent color reagent selected from the group consisting of ninhydrin and hydrindantin and mixtures thereof;
• and,
• subsequently causing said article to come into contact with the skin of said person, thereby causing a colored reaction product to be formed on the skin of said person.

A method of chemically labeling a thief of an article comprising first contacting at least a portion of said article prior to its theft with a latent color reagent selected from the group consisting of ninhydrin and hydrindantin and mixtures thereof, thereby causing a colored reaction product to be formed on the skin of the thief upon handling said article after its theft.