The search covered about 2 acres surrounding the pond. The investigators noticed that grass surrounding nearby power line poles was wilted and discolored. They speculated that a herbicide might have been used on the grass. A common ingredient in herbicides is arsenic in any one of a variety of forms, including arsenic trioxide, sodium arsenite, monosodium methanearsenate, and disodium methanearsenate. The last compound is in the disodium salt of methanearsenic acid, CH3AsO(OH)2, which is very soluble in water and thus finds use as the active ingredient in many herbicides. The herbicidal activity of disodium methanearsenate is due to its reactivity with the sulfhydryl (S---H) groups in the amino acid cysteine. When cysteine in plant enzymes reacts with arsenical compounds, the enzyme function is inhibited and plant eventually dies. Unfortunately, similar chemical effects occur in animals as well. The investigators therefore collected samples from the organs of deer. They planned to analyze the samples to confirm the presence of arsenic and, if present, to determine its concentration in the samples.