Sandeep Singh, a 41-year-old businessman from Varanasi, Uttar Pradesh, has been hospitalized due to suspected thallium poisoning, leading to an attempted murder investigation. Singh, who previously served as the national general secretary of the Samajwadi Party Chhatra Sabha, began experiencing severe symptoms in late February 2025 while in Gurugram. Initially suspected of having Guillain–Barré syndrome, medical tests later confirmed the presence of thallium in his bloodstream. His wife, Khushboo Singh, filed a complaint that led to the registration of an FIR under Section 109(1) for attempted murder at the Kotwali police station. The police are currently investigating how the poison was administered, with potential sources including travel, business meetings, or food. Thallium, described as the 'poisoner’s poison' due to its colorless and tasteless properties, poses significant challenges for detection, raising alarm over the case's implications. The investigation continues as authorities seek to identify the perpetrator.