A 55-year-old woman presented with fatigue, headaches, nausea, vomiting, diarrhea, vertigo, weight loss, abdominal pain, and excessive salivation. Her physical examination revealed swollen eyelids, partial limb paralysis, increased skin pigmentation on palms and soles, and white bands on fingernails. Laboratory results showed low ATP production, high arsenic levels, and abnormal cell death due to lack of ATP. She was diagnosed with mitochondrial malfunction due to the low ATP production and cell death not caused by programmed cell death. It was determined that her significant other had poisoned her with arsenic, likely due to previous marital stress and newly acquired wealth from a lottery win.