Convicted fraudster Stephen Seddon, 46, had once before tried to murder his father, Robert Seddon, 68, and mother, Patricia, 65, by driving into a canal with them strapped in the back seats in a faked road accident.
Seddon then "played the hero" in the aftermath of the "accident" after aborting the murder plan when bystanders went to their aid in the submerged car.
But after that plan failed, four months later he shot the couple to death with a sawn-off shotgun at their suburban home in Sale, Greater Manchester.
His parents had made him sole beneficiary of their £230,000 estate in their will - and paid with their lives.
Today, the father of three, from Benevente Street in Seaham, County Durham, was convicted of two counts of attempted murder on March 20 last year and two counts of murder on July 4, after a five-week trial at Manchester Crown Court.