Hang Yin Leung, 64, was knocked over and held down after she opened her door to six men who pushed into her home and stole cash and jewellery.
It happened at about 18:00 GMT on 31 January at Orne Gardens, Milton Keynes.
She died in hospital on 11 February. Thames Valley Police are treating her death as murder.
Keith Leung said: "When you think of burglary, you think of lost possessions, lost petty cash, but I lost a dedicated mother and a lifetime friend.
"She was also a dutiful officer in the Hong Kong Police and she spent her whole life helping others where she could."
Mrs Leung was at home by herself on 31 January when she answered a knock on her door.
Police said a man asked if she was alone - and left. A short time later Mrs Leung answered a second knock. This time six men forced their way in and ransacked her home.
She was held down on the ground with a hand over her face.
The men, who were white and wore dark clothing and covered their faces, left by running down Orne Gardens towards Lacy Drive.
Mrs Leung was able to give police a statement the following day before becoming ill.
Det Supt Simon Steel, of Thames Valley Police, confirmed she died in Milton Keynes Hospital as a result of the injuries she received in the assault.
He said some items were recovered near Aylesbury on the day of the burglary, but appealed for two missing pieces - a 1991 Oyster Rolex watch and Mrs Leung's Hong Kong police long service medal.
"This is a despicable crime that has targeted a frail woman, at home, alone," he said. "They stole not only her possessions, but her life."
The son of a "dedicated mother" who died 11 days after a cold caller assaulted her has appealed for information about her killing.