Dario Patrizi, 61, was driving his Nissan Terrano to a Napocor power plant in Botocan when an unknown assailant from another vehicle shot him at about 2:30 p.m., police said.
Patrizis body was found slumped with a bullet wound in the left chest inside his car, along the national highway in Cavinti town, about 70 kilometers southeast of Manila, Galang said.
The Italians compatriot, Domincio Dicandia, 56, chief mechanic of the same power company, was being questioned by police, Galang said.
The two Italian men have been staying in Paizenzan Hotel in the nearby town of Pagsanjan and have been working for a private company (CMC Ravenna) that has a contract to maintain Napocors power stations in the Laguna towns of Botocan, Kalayaan and Caliraya.
Martin Brook, second secretary of the Italian Embassy, said there were no indications that terrorists were behind the killing.
Patrizi was to leave for Italy tomorrow to be reunited with his family. Arnell Ozaeta, Ed Amoroso, Christina Mendez and Rene Alviar