The chilling minute-long video in which the woman - in her 30s - vowed to come back from the dead and wreak vengeance has gone viral.
A source close to the family claimed the woman died in Taman Sri Muda area of Shah Alam last weekend, the Malaysian Star reported.
The woman was recorded as saying in Tamil: "My child and I are going to die. I can't live without my husband and I can't live without my child.
"But now, I will take revenge by killing my child."
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"Only a parent will know the pain of killing a child. Do something for (name not clear), that's all," she adds.
The source said the woman's husband died in February, about a month after their wedding.
However, no details as to how he passed away were given in the report.
The source also claimed the couple's daughter, who is over a year old, died on the same weekend as her mother.
According to the source, the couple, then unmarried, had been living together after the birth of their child.
He alleged that the woman was suffering from depression after her husband's death.
He also lambasted those involved in uploading the video on social media.
"What they did is inhumane. The family is already suffering. Seeing the video would only add to their pain," the source said.
However, the police does not have "sufficient evidence to link the two deaths", Abdullah was quoted as saying in the report.