Singh, who was questioned by the SIT, said Sunanda mentioned to her about the IPL issue a day before she was found dead in a luxury hotel, sources said.
They said the SIT will take help of the Economic Offences Wing of the Delhi Police to examine the business model of the erstwhile IPL Kochi franchise and to understand the controversy surrounding it.
The investigators will also examine whether the IPL controversy had anything to do with Sunanda's death.
Asked about the issue, Delhi Police Commissioner B S Bassi said that if needed, the SIT will examine financial transactions of the IPL franchise.
"There are a number of things. It can be background and it can be motive also. If we need to see any financial transaction to understand that, if we need to see the company formation and financial background, then we will look into it," he said.
Bassi also indicated Tharoor can be questioned in this connection again in "some days".
"Whatever we had spoken to him during the first questioning is being analysed and if we need further questioning, it will be done. Since it is a very involved case, there would be a need to talk to him again, so the SIT will call him again in some days," he said.
In her statement to the SDM on January 20 last year, Nalini Singh had said that she had spoken to Sunanda a day before her death over phone and that she had expressed her unhappiness over Tharoor's alleged affair with Pakistani journalist Mehr Tarar.
The sources said Singh told the same things to the SIT which has been questioning journalists who had spoken to Sunanda a day before her death over phone.
"I was examined as Sunanda had telephoned me on the same day she died," Singh, who was questioned at Sarojini Nagar Police Station for nearly 80 minutes on Friday, told reporters.
Singh also claimed that Sunanda wanted to talk to her regarding the IPL and quoted her as saying that she had "taken the flak for him (Tharoor) in the IPL (controversy)".
The IPL controversy had broken out in early 2010 when Tharoor was minister of state for external affairs. There were allegations that he had "misused" his office to ensure that Rs 70 crore, which was equivalent to 19
Sunanda, who was then a friend and yet to become Tharoor's wife at that time, had refuted allegations of any wrongdoing. She had also denied that she was acting as the front for Tharoor in the Kochi IPL franchise.
Later, she quit Rendezvous Sports World after deciding to return her free equity worth Rs 70 crore to the franchise.
"As I told you, all those people, evidence and things which are relevant in the case will be taken into account. So for this, the SIT has questioned Nalini Singh so that we can get the information from her because in the past she had said a few things before the media," said Bassi.
"We do keep ourselves aware of what is being said in the media but we have to take these things formally into cognizance as well. So we have spoken to her," he added.
Delhi Police had started questioning journalists to whom Sunanda Pushkar had spoken hours before her death in January last year amidst their efforts to piece together the sequence of events that preceded her demise in mysterious circumstances.
On Thursday, the SIT had also questioned another television journalist, Rahul Kanwal in this connection.
Talking about the happenings of a day before Sunanda's death, Kanwal said in a statement yesterday: "On January 16, when the spat between Shashi Tharoor and Sunanda was splashed all over the news channels, I reached out to Sunanda asking her if she was keen on doing an interview to talk about the 'IPL scam' she had been referring to in her tweets.
"She had spoken to us on the phone the previous night and I wanted to know if she wanted to do a full length interview. I was actually half hoping that she would say no."
Kanwal has quoted Sunanda as saying that she had "tuberculosis in her stomach".
"Much to my surprise, Sunanda immediately agreed to do the interview. She was distraught when I spoke to her. 'I have tuberculosis in my stomach' she told me and added, 'I'm going to die very soon. But before going I'm going to expose Shashi for what he's put me through. I will take him down'" he quoted her as saying in his statement.
There has also been a talk that the 52-year-old wife of Tharoor had planned to hold a press conference on January 17, the day she was found dead.
Delhi Police filed a case of murder in the case on January 1 this year and an SIT was formed to probe the case. The SIT has so far questioned several people, including Tharoor who was quizzed on Monday for around four hours.
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