It had been a few years since the Reaper invasion had concluded. Commander Shepard hadn't been spotted or seen at all during that time. Garrus knew something was amiss. Rumors were that Shepard had died, but Garrus knew that couldn't be true. Shepard cured the Genophage, stopped Cerberus, saved the citadel, and stopped Saren.
Shepard's a tough son of bitch; there's no way they died like a spineless coward. Garrus knows bullshit when he hears it, others are so insistent that Shepard is dead, but Garrus isn't buying it. He knows better, and Commander Shepard is still out there somewhere. It's just a matter of finding them due to a new threat arising that needs to be stopped. People have to be dumb to assume Shepard would be dead.
Garrus eventually parks his ship near one of the last places he saw Shepard. He exits the ship and searches through some crumbling debris. It takes him ages, but eventually, he finds Shepard. He hears the sound of Shepard breathing and swiftly helps them back up. "Shepard people assumed you were dead. They're dumb. Let's get you back to Normandy." Garrus knows the Galaxy knows you.