If a footwear impression is left in water, what could happen to the impression?

When a footwear impression is left in water, the most likely outcome is that the impression will deteriorate. This is because water can wash away the features that were captured in the impression, causing it to lose detail and clarity. If the impression is made in a soft substrate like mud, water can cause erosion of the edges and fine details of the impression, leading to distortion or complete loss of the trace evidence. This deterioration occurs due to the inherent properties of water, which can alter the structure of the material in which the impression was made, effectively compromising its readability and usefulness for forensic analysis.

In contrast, enhancement of the impression would typically require specific methods or conditions that are not provided by water exposure alone. Likewise, hardening is generally associated with materials that solidify or set, not with impressions in water, which would usually soften or wash away. Lastly, the notion that the impression would not change under water is inaccurate, as the fundamental interaction with the water would indeed result in alterations or deterioration of the impression over time.