Kozhikode: The police might have a tough time proving the multiple murders of Koodathayi if the prime suspect, Jolly Joseph, used cyanide to kill her husband, in-laws and three others, forensic experts said. The deadly chemical has a tendency to disintegrate fast and its traces may not be present in the bodies exhumed after all these years.

Jolly Joseph, aged 47, is accused of poisoning her family members between 2002 and 2016. A post-mortem of her husband's body in 2011 revealed traces of cyanide but the local police closed the case as suicide for want of any complaints from the family. The crime branch has got all the bodies exhumed and sent the remains for forensic tests.

A scientific investigation could be challenging because of the time gap between the crimes and the probe. When bodies decay, they produce small amounts of cyanide. Though tests are available to differentiate between cyanide from the natural decaying process and cyanide ingested before death, the time gap could affect the accuracy of the studies, experts said.

The investigating team has no precedent in Kerala to follow in this case. The state police have decided to send the remains to labs abroad. Even the Central Forensic Laboratory relied on foreign labs to test the remains of Sunanda Pushkar, the wife of Shashi Tharoor MP.

The disintegration of cyanide may be slower in bodies buried in dry areas but the climate of Kerala leaves little to hope for. 

Potassium cyanide, which is used by goldsmiths, comes with impurities, making it less lethal. When potassium cyanide interacts with hydrochloric acid which is found in human bodies makes it potent. The presence of hydrochloric acid decreases as people age, making them less susceptible to the effects of cyanide.

If Jolly Joseph used cyanide, she is likely to have used potassium cyanide. A relative and a goldsmith are also in custody for supplying her with the chemical. In that scenario, she would have laced her victims' food with a good amount of impure cyanide to ensure their death or exposed them to the poison over a long time, experts theorised.