What type of light source is considered effective for investigating sexual assault cases?

Ultraviolet light is particularly effective in investigating sexual assault cases due to its ability to enhance the visibility of bodily fluids such as semen, saliva, and vaginal secretions, which may not be easily visible to the naked eye. When these fluids are exposed to UV light, they can fluoresce, making it significantly easier for forensic investigators to identify and collect evidence at a crime scene. This characteristic of UV light allows for a more thorough investigation and aids in securing vital evidence that can be critical in sexual assault cases.

The other types of light sources have more limited applications. For example, LED lights can provide illumination but do not possess the specific properties needed to highlight biological materials. Infrared light is useful in specific contexts, such as detecting hidden objects or prints, but it is not as effective for revealing biological fluids. Fluorescent light can assist in some situations but does not offer the same degree of enhancement for bodily fluids as ultraviolet light does. Thus, UV light stands out as the most effective choice in this context.