A "suicide" note recovered from the scene of the incident mentioned "family issues" as the reason behind the extreme step.
Dr Rajesh Agarwal, a senior doctor, at the nursing home where Das was undergoing treatment, had on Saturday said that many organs of the officer's body had stopped functioning. He was on life support in the intensive care unit.
He died during treatment Sunday", said an official spokesman, adding Chief Minister Yogi Adityanath has expressed deep condolence to the family members of the young IPS officer.
Das had spoken to circle officers on Tuesday night about patrolling.
A police official said: "The (suicide) letter stated that he was doing so (taking his life) because of family issues. The letter was addressed to his wife and further stated that he loved her a lot. At the end of the letter, it stated that no one else was responsible for it."
At 4 am on Wednesday, his wife, who is a doctor, noticed that his health had suddenly deteriorated.
He was rushed to a government hospital from where he was shifted to a private nursing home in a serious condition.
Uttar Pradesh Director General of Police O P Singh had visited the hospital on Saturday. The body has been sent for post mortem which will be carried out by a panel of doctors, additional DGP (Kanpur zone) Avinash Chandra said in Kanpur.
Preliminary investigations indicated that the officer was in acute depression for the past few days and had searched a website looking for ways to commit suicide in an easy way, Chandra said. He said Das consumed a powder that he had asked his domestic help to fetch him from the market for killing rats.
"He had worked till late in the night on Tuesday. His behaviour was very good. Now, for what reason he had consumed a poisonous substance will be probed," the ADG said, adding the police department had nothing to do with the matter.
Senior police officers including DGP, ADG (Law and Order) and others expressed grief over the demise of the IPS officer.