The trial heard Dunkley had given up his job to look after Cummins, a paraplegic, and that his daily tasks involved shopping, giving Cummins his medications and carrying out banking transactions.
However the court has heard the ex-boxer bullied and threatened him and never paid him a penny, despite promising him money.
Mr Harbage said one motive for the murder may have been for Dunkley to "free himself" of Cummins and the way he "dictated his life" or to "get at Cummins' money".
Dunkley, who the court heard owed around £16,500 to creditors, has admitted a charge of preventing a burial but denies murder.
He claims Cummins died of natural causes in his sleep and that he panicked and chopped him up with a chainsaw.