The present invention relates to a composition and method for the detection of a detectable product formed from a compound of the present invention in the body of an individual. The detectable product may include a halide or a benzenetriol-based or benzenetetrol-based product of a dehalogenation reaction in the presence of FROS. In many embodiments, an indigo-like product formed from an indigogenic compound of the present invention may also be a detectable product for diagnostic purposes. This indigo-like product may have a higher residence time in tissues where it is formed, thus providing a detectable product localized to sites of high FROS. An indigogenic compound containing one or more radioactive isotopes is further provided for therapeutic purposes.