The 66-year-old oligarch was found dead at his home west of London Saturday afternoon by a bodyguard who had not seen him since Friday night, The Guardian reported.
The findings of an autopsy conducted by a Home Office pathologist were due to be released later Monday or Tuesday.
Berezovsky's body was found in a locked bathroom. Family and friends have said he was fully clothed. There was no blood, but a scarf was found at the scene.
He had reportedly suffered with depression for several months. He lost a court suit last year to his former business partner, Roman Abramovich, and had mounting debts.
There is no evidence of a third person involved his death, police say.
Thames Valley police say they are "building a picture of the last days" of Berezovsky's life.
Ilya Zhegulyov, a Russian journalist who interviewed Berezovsky the day before he died, said he looked "very depressed and very lost."
He was the third businessman from the former USSR to die in the affluent area of southwest England in the past five years.