"The CFSL report has not been able to give much headway into the probe. It rules out poisoning and hints toward drug poisoning," said a senior police official associated with the probe. (Agencies)
It was expected that the nature of the poison and the quantity could be established after viscera tests at CFSL but the report has failed to do so.
Police sources said that investigators will now take the opinion from the panel of doctors from AIIMS which had carried out an autopsy to shed light into findings of the Central Forensic Science Laboratory (CFSL) report.
The findings in the CFSL report, which was handed over to Delhi Police on Friday, are still inconclusive for the police to file an FIR in the case, they said.
On January 21, a sub-divisional magistrate had directed Delhi Police to investigate the murder or suicide angle in the case after autopsy report has cited the death as "sudden and unnatural" while the cause of death was mentioned as poisoning. The SDM has also been informed about the CFSL report.
Sunanda, 52, was found dead in a 5-star hotel in South Delhi on the night of January 17, a day after her twitter spat with Pakistani journalist Mehr Tarar over an alleged affair with Tharoor.
In a report to the police, the SDM, who had recorded the statements of Sunanda's brother, son, Tharoor and his staff, had said that no family member suspected any foul play in the death.
The autopsy report had mentioned more than a dozen injury marks on Sunanda's both hands and an abrasion on her cheek which suggests a "use of blunt force", besides a "deep teeth bite" on the edge of her left palm. Viscera samples were preserved after the autopsy at AIIMS and were sent to CFSL for further tests.
The search and seizure memorandum of the police, which is a part of the report, mentioned finding of mix of two drugs -Alprazolam and Excedrin. Excedrin is a combination of acetaminophen, aspirin, and caffeine while Alprazolam is an anxiolytic.
The probe into the case was handed over to the Crime Branch on January 23. However, the case was transferred back to the South District police two days later on January 25.
"The CFSL report has not been able to give much headway into the probe. It rules out poisoning and hints toward drug poisoning," said a senior police official associated with the probe.