Luminol is used in forensic investigation to detect concealed bloodstains; however, current research suggests that luminol cannot detect bloodstains cleaned using oxygen-based cleaners because they denature the hemoglobin protein. Luminol cannot bind the denatured hemoglobin. The goal of the present research is to develop a technique to circumvent this issue by reversing the protein damage caused by oxygen-based cleaners, making oxygen-cleaned bloodstains detectable by luminol. First, previous research was replicated to confirm that oxygen-based cleaners prevent luminol detection. Then, denaturation was partially reversed using a urea solution and the bloodstain was re-tested with luminol. Observations were made in a dark room. Chemiluminescence was quantified by spectrophotometry. Reversing the denaturation of hemoglobin enabled luminol to bind the protein and chemiluminesce to occur, which allowed us to detect bloodstains. Developing a protocol to make bloodstains cleaned with oxygen-based cleaners detectable by luminol will allow investigators to detect bloodstains that were once undetectable.