Lucknow: A Varanasi-based businessman was poisoned with thallium, a rare and highly toxic substance, prompting the police to register a case of attempt to murder in an incident reminiscent of the slow-motion poisoning plot in the recently released Hindi film. Durandar: The revenge movie.
The victim has been identified as businessman Sandeep Singh (41), a former national general secretary of the Samajwadi Chhatra Sabha Party, an officer said.
“A First Information Report (FIR) under Section 109(1) of BNS (attempt to murder) was lodged at Kotwali police station against unidentified persons in Varanasi on Wednesday evening on the basis of a complaint by Khushbu Singh, wife of Sandeep Singh,” Kotwali SHO Dayashankar Singh said.
The SHO added that the police are investigating whether the suspected poison was ingested during travel, hospitalization, business meetings or through food consumed outside the home.
Singh, who runs two transport companies associated with road construction logistics, is currently undergoing treatment at his residence in Lucknow under medical supervision, his family members said.
This case has raised concern due to the nature of the rare poison, which is difficult to detect and often mimics neurological disorders in its early stages. The victim’s wife alleged in her complaint that an unknown person may have injected the poison with the intent to kill. The family became suspicious after doctors in a Mumbai hospital discovered traces of thallium in his blood.
According to the FIR, Singh first fell ill in late February 2025 while in Gurugram, where he was accompanying an acquaintance undergoing treatment. The initial symptoms – fever, tingling in the legs, body aches and vomiting – gradually worsen into an acute neurological condition.
He was first admitted to Medanta Hospital and later transferred to Max Super Specialty Hospital, where doctors reportedly suspected Guillain-Barré Syndrome (GBS). As his condition deteriorated, he was airlifted to BD Hinduja Hospital in Mumbai, where toxicology tests confirmed the presence of thallium in his bloodstream, the FIR said.
“We first filed a zero FIR at Mahim police station in Mumbai on March 30, 2025, soon after doctors suspected poisoning,” said Ajit Singh, Sandeep Singh’s brother. “The police then transferred the complaint to UP Police as the place where the incident occurred did not fall under its jurisdiction. However, the case file was sent back to Mumbai about five months later, delaying the official registration and investigation,” said Ajit Singh, Sandeep Singh’s brother.
“The FIR was finally registered on Wednesday, (weeks) after the Mumbai Police Commissioner raised the matter again with UP Police officials on February 27, 2026 regarding transfer of the complaint and progress of the investigation,” he added.
Medical literature describes thallium as a “poison poison” because it is colourless, odorless and tasteless, making it extremely difficult to detect if mixed with food or drink.
Giving a forensic perspective, Dr Richa Chaudhary, head of the department of forensic medicine and toxicology at Dr Ram Manohar Lohia Institute of Medical Sciences, Lucknow, said the symptoms vary depending on the dose and form of the compound, such as thallium sulphate or acetate. She added: “Mild toxicity may present with nausea, vomiting, and diarrhea, while severe poisoning can lead to vomiting blood, severe diarrhea, and even death due to respiratory failure.”
Chaudhary added that thallium poisoning often follows a clinically recognizable timeline. “Peripheral neuropathy usually begins after two to three days, while alopecia develops after about 10 days,” she said, noting a classic diagnostic triad — skin rash (often in a butterfly distribution on the face), peripheral neuropathy and hair loss — that is considered highly suggestive in toxicology evaluation.
Experts said the toxin destroys the nervous system by mimicking potassium and entering cells, leading to gradual neurological deterioration.
Police said the investigation is ongoing.
