William Holmes, 66, gave his wife a strong tranquilizer before stabbing her in the chest on the night of November 12th 2012, La Repubblica reported on Monday.
The couple were originally from California and had lived in Italy since 1979, Gazzetta del Sud reported.
The sentence for killing his wife, Patricia Ann Holmes, was more lenient than the 15 years requested from the prosecution given the special circumstances of the crime.
The victim had suffered from rheumatoid arthritis for 10 years and was in increasing pain and unable to move, the newspaper said.
Holmes said his wife had asked for his help to end her life a few days before he stabbed her. After killing her, Holmes wrapped the body in a cloth and waited a number of days before turning himself in, La Repubblica said.