The echo of a gunshot

His life seemed a contradiction at times. If he needed to stay awake, he would get sleepy. If he needed to go somewhere, he ended up stuck. And when he needed to concentrate, he got distracted. Like right now.
It was the myriad sounds that captivated his attention at this crucial moment. He needed to have his attention focused, instead he could hear electricity pop from the nearby transformer. The sound was like lightning in the air, a sizzle then pop. Repeated. Over and over and over.
He had been sitting there so long that he didn't really fear the transformer blowing, his assumption after examining the pole was that this was a common occurrence and nothing to be concerned about. But in reality it didn't matter. The resulting explosion would provide him with the opportunity he was waiting on. Which is one of the reasons why he had been sitting here so long in the first place. "In fact," he reasoned, "the transformer exploding would actually work in my favor." But without the transformer exploding on its own, he didn't risk shooting it for fear that he would give away his position. Which was the other major reason why he had been sitting here motionless for so long. He needed this shot.
Most clients were vague on how they wanted their problems dealt with. They wanted someone discreet, thorough and effective. Of which he was all of  and more. This desire for lack of information allowed him to be more persuasive and non-lethal in his methods. Sometimes, though, non-lethal methods didn't solve the problem. "And sometimes, the client is very specific in how they want the situation handled." He muttered softly aloud.
There he was again, distracted. Luckily for him, the target hadn't emerged from his hide-out yet. Andrew didn't really know what the target had done, or why he was supposed to dispatch the target in this specific manner. And Andrew didn't want to know. He didn't get paid to ask questions. He was paid to provide solutions that conventional methods couldn't. Questions weren't encouraged by his clients.
Bzzzzzzz
The sound was getting louder from the transformer, perhaps Andrew would get lucky after all. He raised the rifle to his shoulder, peering down the scope. The range was good, he was on the mark he had picked out earlier, based upon the target's height. The target wasn't a tall man, and his bodyguards made up for that lack. They were behemoths. But they left gaps that a bullet could find its way to. You just had to aim correctly.
While Andrew was checking the wind and weather, he heard the door open. The creak of the hinges carried across the distance between them. Andrew slowly lifted the rifle to his shoulder and peered down the scope once again. This time, there was much to look at, as Andrew scanned the people coming out of the door, looking for the target.
Seconds passed, but they felt like hours to Andrew as he searched for the target. Soon, he found the opening he sought. With an exhale of breath, Andrew squeezed the trigger. The recoil of the rifle jarred him to the bone, Andrew knew it was going to leave a nasty bruise. The bullet, meanwhile, found it's mark. Even surrounded by bodyguards, Andrew had found his mark.
With a motion smooth from many hours of practice, Andrew was chambering another round even as he exhaled from the first shot. He watched and waited. Sometimes in an operation like this, you had shoot twice. The gun held steady, waiting, watching. The target lay on the ground in an ever-widening pool of blood.
Satisfied that he had fulfilled the contract, Andrew stood up and begin to gather his things. It would take police 30 to 40 minutes to even realize that the shot had come from this distance. That was a lifetime to someone with Andrew's skill sets.
As Andrew started down the stairs, the transformer continued its eery noise.