Inside Delhi's 2021 Thallium Poisoning Case: A Family, a Toxic Plan, and Justice Pending

In early 2021, a quiet neighborhood in Delhi was shaken by a case that sounded more like a crime novel than reality. Varun Arora, a 37-year-old real estate businessman, was accused of methodically poisoning his wife and her family members using thallium, a toxic heavy metal once notorious for its use in covert assassinations. What began as a family meal, soon unfolded into a complex forensic investigation involving rare toxicology, online footprints, and tragic loss.

What happened?

The incident occurred at the home of Varun Arora’s in-laws in Inderpuri, New Delhi, where several members of the family fell mysteriously ill after consuming fish curry allegedly laced with thallium on 31st January 2021.

At first, his sister-in-law, Priyanka Sharma fell ill within few days on 2nd February and was admitted to BLK hospital, Delhi and died during treatment on Feb 15th. His mother-in-law, Anita Devi Sharma and his wife, Divya Arora, followed battling for their life at Sir Ganga Ram Hospital. Anita Devi passed away on March 21 and Divya, the perpetrator's wife who remained in a coma from the time of admission till she passed away after 40 days on April 8th. The father-in-law, Devinder Mohan Sharma and a household helper also reported similar neurological and gastrointestinal symptoms but survived after medical intervention.

Suspicions and Arrest

At first, the deaths puzzled both doctors and police. The victims had presented with hair loss, burning sensations in the limbs, and progressive weakness, symptoms that could have been mistaken for neuropathy or heavy metal exposure. Priyanka was initially diagnosed with GBS (Guillian Barre Syndrome). But it was the death of the mother-in-law which was a turning point. Toxicological tests ordered by hospital clinicians later confirmed the presence of thallium, in the mother and daughter, a chemical element with no taste or odor, and capable of causing fatal multi-organ failure even in minuscule quantities.

They informed the police, and an investigation began on March 22nd. Reacting to the complaint filed by the father-in law over suspicions on Varun Arora, the police arrested him for further questioning on March 24th.

When Delhi Police began retracing the victims’ final days, suspicion on Varun Arora were soon confirmed. Investigators found that he had been present during the meals and had personally handled the food. He also made sure that his twin children did not eat the poisoned food but instead drank some milk. When the father-in-law asked on why he was not eating the fish, Varun lied about having a stomach pain. He also served the food to the sister-in-law personally after she returned from the work in the evening.

Upon forensic examination of his electronic devices, police discovered search histories about lethal poisons, "how to make someone very sick" and other methods of slow killing, and historical cases involving Saddam Hussein’s use of thallium. Reports also indicated that he had ordered the compound online, disguising it as a chemical reagent for laboratory use. He forged the papers for the license to obtain the chemical and even re-ordered it since his wife was not falling sick like the initial victim. This indicated multiple times of ingestion. He allegedly googled about slow poisoning and selected Thallium for its properties. He rejected Lead and Mercury since death would have been immediate with it even though it was more easily available. On the other hand, Thallium took much longer to exhibit symptoms and by the time symptoms worsen, the blood stream would be devoid of the toxic metal and concentrated in the vital organs like brain and liver. A small bottle containing traces of the substance was later seized from his home in Greater Kailash-I. To mislead the investigation, he consumed thallium in a small amount after the initial questioning. He sought treatment and produced the blood reports with the presence of the toxic metal when asked to be present for further interrogation.

The forensic evidence strengthened the case. Samples collected from the victims’ hair, nails, and internal organs revealed high concentrations of thallium. Forensic pathologists explained that such biological materials retain traces of the metal long after ingestion, helping confirm chronic exposure. Investigators also pieced together timelines of symptom onset — all coinciding with meals allegedly prepared or served by Arora.

The Motive

Although initially an extra-marital affair was suspected as the motive, as the investigation deepened, a disturbing image began to emerge. According to police statements and court documents, Arora harbored resentment toward his in-laws after his wife underwent an abortion (because of medical advice due to some complications to her and the unborn baby) against his wishes the previous year. He reportedly believed the unborn child was a reincarnation of his deceased father who had passed few months before and blamed her family for supporting her in the decision. In what authorities described as a calculated act of revenge, he is said to have plotted to eliminate her and relatives, poisoning them over several meals.

Rarity of Thallium Poisoning

The case quickly drew public attention for its rare use of thallium — a substance that is tightly controlled due to its extreme toxicity. Thallium was once used in pesticides and rodenticides but is now banned in most countries. Modern cases of poisoning are uncommon, and deliberate homicides using it are even rarer. Its mechanism of action disrupts potassium-dependent cellular functions, leading to nerve damage, alopecia, and severe gastrointestinal distress before culminating in cardiac and respiratory failure.

Thallium poisoning, though rare, can be difficult to diagnose early because of its non-specific presentation. Symptoms such as peripheral neuropathy, hair loss, and abdominal pain often mimic common conditions. Toxicologists have since urged clinicians to consider heavy metal screening when faced with unexplained neurological symptoms, particularly in clusters or familial cases.

Judicial Proceedings

By mid-2021, Delhi Police had filed a detailed chargesheet against Varun Arora under Sections 302 (murder), 307 (attempt to murder), and 328 (causing hurt by poison) of the Indian Penal Code. Expert witnesses from government forensic laboratories confirmed the chemical identity of the substance. Doctors from Sir Ganga Ram Hospital and All India Institute of Medical Sciences (AIIMS) submitted medical opinions establishing cause of death consistent with thallium toxicity.

However, the absence of postmortem on Priyanka, the first victim has made the judicial process slow. As of 2025, court records indicate that the trial remains ongoing, with multiple forensic experts deposing before the sessions court. The defense has challenged the chain of custody of the samples and alleged procedural lapses during recovery, delaying a final verdict. The families of the deceased continue to seek justice under a social campaign known as “Justice for Priyanka, Anita & Divya.”

The investigation also highlighted the digital dimension of modern crimes. Arora’s internet activity, including search terms like “slow poison with no taste,” played a key role in reconstructing intent. Forensic analysts from the cybercrime unit demonstrated how online footprints now serve as critical corroborative evidence alongside physical toxicology.

As the case awaits final judgment, it remains one of India’s most significant examples of forensic toxicology in action.

References

1. Devender Mohan Sharma vs. State of NCT Delhi & Ors. 2021. Delhi High Court, August 25. https://indiankanoon.org/doc/26983454/.

2. Wronged. “Psycho Killer Was Hiding in Their Family! | Varun Arora Case | New Delhi | Hindi | Wronged.” YouTube video, 2021. https://youtu.be/53AgZyLv6Sk.

3. Manral, Mahender Singh. 2021. “Thallium Murders: Businessman’s Wife Also Succumbs to Poisoning.” The Indian Express, April 9. https://indianexpress.com/article/cities/delhi/delhi-thallium-murders-businessman-wife-dead-7265481/.

_MSM