According to Scotland Yard, post-mortem examinations have revealed that Poonam had been killed by "compression of the neck", while her husband died of "suspension caused by hanging".
Kumar's death was not seen as suspicious from the start, implying a suicidal act.
"Officers were called at approximately 3.10pm on Friday to an address in Priory Way, Western Road, Southall, following concerns for the welfare of residents there," a Metropolitan Police spokesperson said.
"Officers attended and discovered the bodies of a man and a woman, both in their 30s. Both were pronounced dead at the scene," the spokesperson said.
The couple's next of kin have been informed and the police have confirmed that they are not looking for anyone else in connection with the deaths.
Officers from Scotland Yard's Homicide and Major Crime Command are investigating the woman's death as a murder.
According to local media reports, Kumar may have strangled his wife before taking his own life.