The politician - Prasad Milinda, a member of the Weligama Pradeshiya Sabha.
Several close contacts of the PS member's family have contracted Covid-19 and therefore, he too has been quarantined, police say, adding that this is the reason for the delay.
His younger brother - Niresh Krishantha has said that the assault had taken place over a land dispute.
The assaulted couple are being treated in the Matara Base Hospital and the Ahangama hospital. The mother is being treated at the ICU.
Niresh has added that his son had recorded the whole incident on his mobile phone.