Omicron [1963 - Italy] sci fi

During a walk, two little brothers, their sister, and a caregiver find the body of a worker, Angelo Trabucco, stuck in a concrete pipe. When the authorities come to collect the body, they are puzzle by its stiffness, much greater than normal rigor mortis. It turns our that the body possessed by Omicron, an ethereal inhabitant of the planet Ultra, whose race want to take over the Earth. As the body of Trabucco-Omicron is prepared for an autopsy, it begins to come to life. Omicron has a tough time learning to control the body. Now that he is once again alive, he is rehired by the SMS factory where he used to work. He is able to complete his task of making gyros at an unbelievable rate, 3600 an hour. At first, the trade unionists seem lazy to him because they work so slowly in comparison. Through the kindness of a woman lunchroom worker, Lucia, he then becomes an outspoken voice in support of the workers. This helps him discover how human society really works. He is able to advise his off-planet supervisors to not kill of humans. He suggests invading through the bodies of leaders and the ruling class. Leave the common rabble to support the upper class.