Elias Suarez was a farmer, husband and father before the apocalypse. Sometime before the events described in "Do Not Disturb" his wife and children died and he buried them, under a tree with a swing attached to it, just outside the farmhouse.
When Brandon's Group, Travis Manawa and Christopher Manawa arrived at the farm Matias was nowhere to be seen, but when the young men, Brandon's Group and Chris, started making a noise in the barn - trying to catch a chicken to eat - he went into the barn and challenged them.
After a short standoff, he reacted to one of the young men (James) killing a chicken by shooting him in the leg. Chris reacted to this by shooting and fatally wounding Matias.