Chad Longko was a trainee in the Galactic Empire. He underwent training as a cadet at the Imperial Academy on the planet Carida, specifically the academy of Carida. Longko began his time at the academy in 5 BBY and finished his training in 1 BBY. General [Rom Mohc] (/article/rom_mohc) supervised the graduation for the cadets that year, and he announced Longko's name, as well as others, to come up and be presented with a special award recognizing their bravery and accomplishments.
The first time Chad Longko was mentioned was in the audio adaption of the short novel Dark Forces: Soldier for the Empire, which came out in 1997. Because the character's name is only spoken in the audio adaption's dialogue, we don't know the exact spelling of his name.