A 7-year-old boy was found dead inside in a washing machine on May 15 at his house in Ho Chi Minh City.
Police said he had possibly got into the front-loader himself, but then was trapped after locking its door.
The child died from asphyxiation, news website VnExpress quoted District 7's police as saying.
The machine was not operating when the accident happened, they said, adding that it did not contain clothes and water.
Another news website quoted a representative of the washer's producer as saying that it has child lock, but the security mode can only be activated when the machine is on.