Ali Qazimaj, 43, told a friend he had 'done a bad thing' shortly after stabbing Peter Stuart, 75, nine times 'with extreme force'.
He then tried to hide the pensioner's body in tarpaulin in a water-filled ditch close to his home in Weybread, Suffolk, before fleeing the country.
Qazimaj denied killing Mr Stuart and his wife Sylvia, 68, whose body has never been found, but a jury today took less than four hours to find him guilty of two counts of murder.
The victims' daughter and son-in-law gasped and hugged one another as the verdicts were read out at Ipswich Crown Court.
Qazimaj claimed he has been "fitted-up" for the killings, even pretending to be the victim of mistaken identity who had never previously visited the UK.
But he was described a 'lying murderer' by prosecutor Karim Khalil QC, who said "damning forensic results" showed fingerprints meant he was the culprit.