Lieutenant Ernesto Zabaleta is a former Systems Alliance marine who can be found on the Citadel Ward Access corridor.
If Commander Shepard has the Spacer background, then he appears on the Citadel looking for a handout.
Zabaleta recognizes Shepard because the Lieutenant was assigned to the SSV Einstein with Shepard's mother but he is now down on his luck, even hitting the Commander up for credits.
During a conference call, Hannah Shepard, the Commander's mother explains that Zabaleta was one of the ground troops at Mindoir and suffers from post-traumatic stress syndrome as a result of what he saw on his mission. Zabaleta turned to alcohol, eventually leaving the service after repeatedly showing up to work intoxicated. Hannah suggests referring Zabaleta to the Veterans Affairs Office on the Citadel, but he is reluctant to entertain that suggestion. Shepard can give up, set up Zabaleta with a grocery store account, or convince him to go.