Sunanda Pushkar's son questioned by police
Menon arrived in the capital on Wednesday after being summoned by investigators.
Sunanda Pushkar, the wife of high profile Congress MP and former Union Minister Shashi Tharoor, was found dead in her suite at a five-star hotel in south Delhi on the night of January 17, 2014.
The death turned a mystery as only a few days before the incident she had publicly accused Pakistani journalist Mehr Tarar of having an affair with her husband.
Almost after a year police registered a case of murder after medical reports said the death was due to poisoning.
The police team has already questioned Tharoor, former Samajwadi Party leader Amar Singh and senior journalist Nalini Singh besides a dozen other persons in connection with the case.