Viscera samples piling up at the Barasat police morgue following the backlog at the State Forensic Science Laboratory (SFSL) risk getting contaminated, derailing several criminal investigations.

Officials said thousands of samples, accumulated over the past one-and-a-half years, were being kept in containers stacked in the open on the morgue premises.

“The samples will be destroyed if the formalin in which they are dipped comes in contact with air. If the containers have been lying in the open for the past year and a half, I fear many of the specimens are no longer ideal test material,” said an official of the Salt Lake laboratory.

To add to the problem, the labels on several containers have worn off, making it difficult for the cops to match a specimen with the corresponding case.

Asked about the samples being left to rot, North 24-Parganas police superintendent Rahul Srivastava said: “A committee has been formed with the district magistrate, district judge and police representatives to speed up the tests. The committee meets every fortnight.”

Viscera samples of victims of unnatural deaths are segregated after post-mortem for forensic tests, the findings of which may help police identify the cause of death.

Morgue sources said the containers were being kept in the open as the building lacked space to store so many of them. “Containers are piling up as the laboratory has stopped receiving samples because of their backlog. So we have no option but to keep them in the courtyard,” said a morgue official.

A senior health department official in North 24-Parganas said it was the responsibility of the police to take the samples from the morgue to the laboratory. “Once our doctor segregates the body parts, including viscera, cops are supposed to carry them to the Salt Lake facility within a month.”

Laboratory director Dhurjyoti Sengupta pleaded helplessness, saying the authorities could accept new samples in bulk only after tests of around 12,000 pending ones were completed. Some officials blamed the backlog on inadequate manpower and infrastructure.