The 45-year-old mother had reportedly dropped her keys in a lift in the city of Ningbo, eastern China.
Xie Hong Feng approached her building manager for help in retrieving them, and he offered to manually move the lift up one storey whilst keeping the door open.
He told local news outlets: "She was taking some rubbish out but on the way down dropped her keys and she wanted me to help her get them.
"I told her I would manually move the lift up one storey while keeping the door open so she could try and get her keys, which she had dropped in the narrow space between the lift and the 5th floor.”
However, when he returned to see if his plan had worked, he was shocked to find that the woman had vanished - leaving her toddler son behind.
He explained: “I then went to see if she had found them but only saw her two-year-old boy standing there.
"When I asked him where his mummy was he said he had pushed her.
"I looked over the edge and saw her body lying at the bottom of the shaft."
As there is no surveillance footage available of the incident, police have said that they will never know what truly happened.
However they have added that, as the little boy has confessed, they will accept that he was most likely the cause of his mother’s death.
They added: “We won’t be pressing charges as this was certainly an accident."
Meanwhile, the woman’s heartbroken husband has said: "The saddest thing is not only is my wife now dead, but my son is facing the prospect of having to bear the guilt of her death for the rest of his life."