Luke had always wanted to become a Law Officer, following in his father and older brother's footsteps. Even from a young age, he had always dreamed of joining a SWAT team in particular. He wasn't as athletic as the rest of his family, but made up for it with sheer determination, intelligence, and pragmatism. Luke could always be found going to the range with his family, reading books, or generally studying dutifully. He graduated high school and entered the academy with no problem, and was well on the road to spreading Law and Order to the world.
Then his dream was stolen from him. He was nearly finished with the academy when society broke down. Knowing there was nothing he could do without help or authority, he quickly made his way to his brother. Together, they formed a group dedicated to protecting and serving whatever sane remnants of society there was, along with his brother's buddies. A decent sized group of experienced police officers was quite capable of taking care of itself for some time. This is when Luke finally put all his skills to good use. He was proficient enough with the available weapons to take down Rotters with little trouble, especially with his brother and other allies by his side. It was his idea to wear "Dog Tags", bananas identifying the wearer at a distance, so they can be picked out from the mass of bodies assaulting the compound if it came down to it. Seeing as he and his brother shared the same last name, he volunteered to wear his upside-down, so they could tell each other apart.
Then one routine day, even this was stolen from him. They weren't expecting anything big that day, and had just gotten a group of new (starving) survivors. Most of the experienced officers where off collecting supplies for them, most where in rags and were almost unarmed on top of having empty stomachs. Luke and his brother were left to hold the fort while they were gone. They always made a great team, and Luke took the duty of helping the new survivors adjust to the situation while explaining their new jobs and duties to them. His brother watched the gate. While Luke was performing a demonstration on firearms safety, he heard gunshots coming from outside. This was nothing odd, of course, so he continued as if nothing had happened. But they became more and more frequent, to the point it sounded like a war was being fought outside the door. Luke got worried, said something hollow to calm down the survivors, and began rushing to the gate with a rifle at the ready. It was too late. He heard his brother give off an uncharacteristic scream of terror. By the time he got there, his brother was gone. The gate had been breached, there was no time to even look for his dog-tag. Luke did what he could to buy time and rushed back to the survivors.
Hardening his heart, he determined that his brother's fighting had attracted a horde. Perhaps his group simply grew too large, perhaps they left too many scents and tracks, perhaps they where just unlucky, but this horde had to have been gathering itself for some time. Luke blamed himself, deciding that it had been one of his own policies or plans that had inadvertently gathered so many in once place. Inadvertently killing his brother, destroying his home, and maybe even killing him and everything he cares about. Even if they had just switched positions, maybe things would be different.
Once back with the survivors, he immediately barked orders. He separated them into small groups, based on friend and family considerations along with what was most likely to survive. He quickly rationed out the supplies and gave the evacuation order, telling them to go to separate destinations to avoid making themselves large targets. Finally, he ordered one of the survivors who has been here since the beginning to set fire to the building. This was determined as a per-planed signal, easy to see and understand from any part of the city: The base is overrun. Evacuate.
After giving off orders as fast as he possibly could, Luke prepared for his job. Distraction. They where coming, but he could hold them off for some time. He prepared a boom-box with some rotting meat, running back out toward the gate to use himself as Rotter bait. This way, he could avenge his brother while atoning for this whole mess. He set up in a relatively safe position, counting on the traps to stall them long enough to give him time for at least this, and blasted the music. He fired off the verity of weapons he had brought, further attracting the horde to himself. He started stalling-somehow managing over ten minutes- when he started running out of ammunition and batteries. Knowing he couldn't hold them off-or put a dent in them-with melee weaponry, he decided to run using a per-planned escape route, attracting as many Rotters with him as he could. Carefully, he fled the city with his walking-dead entourage. He had never expected to survive being the distraction, and is still mystified as to how he did it. Perhaps all his good luck finally caught up with him. He found himself running further and faster than he could before (chocking it up to having a horde chasing him), and eventually lost them in the countryside.
Briefly, he looks down at his dog-tag, thinking about burning it like the building. Instead, he chose to honor the brother who gave his life serving others, and the memory of the group, by keeping it. He turned it right side up, like his brother always had it, and began walking in a random direction, simply wandering and surviving since then....