In its opinion on the FBI report which had said that the samples provided to them were of low volume and degraded, the board was of the view that the case may have led to a complete "botched-up scenario" had the FBI not been consulted.
In its report, FBI stated that due to limited volume and generally degraded nature of the biological specimen submitted, "quantitation" of the identified drugs was not performed.
"This dilution of the sample raised the limits of detection for all analyses performed on item 11 (blood samples)," said the FBI report received by Delhi Police.
Referring to the aforementioned claims, the AIIMS medical board said, "This is a grave issue of concern for our legal investigation system... Which raises serious medical and legal apprehension about the quality of forensic lab report, supervision of legal investigation and custody of biological evidence in cases of death investigation.
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The board further said that appropriate legal remedial measures need to be instituted in this case as well as in the general interests of investigation and natural justice delivery system.
"The medical board is highly afraid that this case of deceased Sunanda Pushkar may have led to a complete botched-up scenario in the absence of the FBI report," the board said.
In its report, the FBI also ruled out the presence of illicit drugs, which includes opioid, methamphetamine (meth) and antihistamines.
However, the board did not rule out the possibility of any injectable poison, in view of a particular mark on Sunanda's body, and said that the FBI report confirmed the presence of lidocaine in her body.
It also said that the Special Investigation Team (SIT)
probing the case should "thoroughly investigate" if any person had access to injectable agents in view of a syringe mark spotted in Sunanda's body.
"I would not like to enter into speculation. What is being published or broadcast in the media could be right or could be wrong. At this point of time, I won't be able to say anything conclusive.
"Once the investigation is complete, we shall send a report to the court. At that point we shall brief media about our findings. And I can assure that the investigation will be complete as early as possible," he told reporters.
"By the time the FBI lab got the viscera samples, the contents had already degraded. There was an unnecessary delay on part of Delhi Police in sending the viscera samples of Pushkar to FBI," said Gupta, who is also the head of AIIMS Forensic Science department.
In January last year, Delhi Police had registered a case of murder in connection with the death of Sunanda. An AIIMS medical board had found poisoning as reason for her death following which the police had sent her viscera samples to an FBI lab in Washington last year.
As police could not firm up about cause of the death based on the FBI report, they requested a medical board of AIIMS to analyse the contents of the report.
51-year-old Sunanda was found dead at a suite in a five- star hotel in South Delhi on the night of January 17, 2014, a day after her spat with Pakistani journalist Mehr Tarar on Twitter over her alleged affair with Tharoor.