How did a drum's weight lead to breakthrough in case of Meerut man's murder by wife?

Muskan Rastogi and her lover Sahil Shukla had called labourers to help dump the drum containing her husband Saurabh Rajput's chopped body in Meerut. Labourers were unable to lift the drum due to its weight and during one of their attempts, its lid came off, filling air with rotting body's stench. Following this, Muskan panicked and confessed to the crime.