Sunanda's death: number of conspiracy theories, little success

The mysterious death of Sunanda Pushkar, wife of the then Union Minister Shashi Tharoor, exactly a year ago at a five star hotel here is still under probe with no major progress in the investigation so far.
On January 1, Delhi Police Commissioner B S Bassi surprised everyone when he announced that the police have registered a case of murder in this connection after the final AIIMS report, handed over to police on December 29, which said that she died of poisoning.
Bassi had said the report has not specified the nature of the poison and how it was administered into her body. The substance is still not clear but the death is due to poisoning, he said.

The police will now send the viscera samples abroad to find out the quantum and nature of the poison while an SIT has been formed to investigate the case from scratch which has already questioned several people in this connection.
But the investigations in the case so far has raised more questions than it has answered, the biggest one being why it took almost a year for the police to register an FIR and why it has never questioned Sunanda's husband Shashi Tharoor in the case.
Delhi Police Commissioner has hinted that Tharoor can be questioned in this case in the next couple of days.

While police probe in the case looked directionless for almost an year, medical and forensic reports have also been confusing.

The post mortem which was conducted on January 18 had indicated toward "alprazolam poisoning" while the forensic report by Central Forensic Science Laboratory (CFSL) and Forensic Science Laboratory (FSL) Rohini completely contradicted it by ruling this out.
Since then, the AIIMS Medical board has given two reports to the police and maintained that she died of poisoning but failed to identify the poison.
The reports ruled out "natural cause" while noting out that all the 15 injuries found on her body, except 'injury number 10' (an injection mark), were caused by blunt force and non-contributing to death.

The injection mark is said to be the "area of interest" for the investigators.