We Catch Aliens

It was a sunny morning, but here in the back alleys of Castries, it was dark and shadowy. It had rained the night before and the ground was still damp where the sun hadn't yet reached it. Well, the dampness wasn't just from the rain. It was from the blood as well.
"What have we, George?" Detective William Murdoch asked, coming to stand beside his friend and coworker, Constable George Crabtree. He could see the body from here, though it was covered by a thick green tarp. One foot was sticking out, wearing an oversized shoe with the laces undone. Probably a drunk who'd gotten killed in a fight, then.
"That's the thing, Sir," George responded, "the woman who found the body says it isn't human."
William glanced at him and then back at the body.
"It looks human to me." He mused.
"Well..." George seemed to be bothered by something, "just come and have a look at it." Both men walked further into the alley, closer to the body. The ground was soaked in blood here and there was a revolting smell in the air, not unlike rotten fish. George knelt down and pulled the tarp away from the body's face. William frowned. The body's skin was bright red, marked with small white stripes. There were fins on its face and a bony crest on its forehead, and its dead, staring eyes were bright yellow.
"Is this some kind of joke?" William asked.
"No, Sir," George said, "we checked to make sure it wasn't a mask, it's not." He stood up, that familiar sparkle in his hazel eyes he got when his rather vivid imagination was running wild again, "Sir, do you think it's a-?"
"No, George," William cut him off, "I don't think it's an alien."
"Well then what else could it be?"
William never got the chance to answer George as the quiet of the morning was shattered by the roar of an engine and a screech of breaks. A big black SUV had just arrived on the scene, coming to an abrupt halt at the end of the alley. A few of the other officers gathered around started to move in, preparing to fend off whoever got out of the car.
The first person of three to get out was a man, probably in his late twenties or early thirties, with brown hair and blue eyes. He was about six feet tall and wearing a suit with a pink and black pinstripe tie. He fiddled with his cufflinks when he got out of the SUV, then noticed the police officers standing around and reached into his pocket to pull out an ID of some kind.
He said (in what William assumed to be a Welsh accent) one word; "Torchwood."
Two other people got out of the SUV behind him, a slightly shorter man in a leather jacket carrying what looked like a medical kit, and a person with golden brown skin, and long golden and red hair wearing a Hawaiian shirt and shorts.
The first man led them over to the body, where William and George were still standing.
"Excuse me," William said, "do you have any authority to examine this body?"
"We've got plenty, mate," the shorter man said, "you heard him, we're Torchwood, now shift."
"Owen," the first man said warningly, then tapped an earpiece he was wearing, "Jack, it looks like the police got here before us, but we're handling it... no, we don't need you to come out here and help." There was a slightly longer pause this time and the man rolled his eyes, lowering his voice the next time he spoke, "yes, dear, everything will be fine, we'll get the body back to the hub in no time. See you then. How did it die, Owen?" That last sentence was directed at the second man.
"Looks like several stab wounds to the chest and stomach," the other man - Owen was his name, apparently - said, kneeling beside the body and peeling back the tarp, "hence all the blood - did I just hear you call Jack 'dear' or do I have wax in my ears?"
"Shut up." The first man growled, his cheekbones turning red.
"Boys, be nice to each other!" The third person said, finally stepping a bit closer. They had a slight Spanish accent, and their voice was familiar. William and George looked at each other before George took a step closer to the strange person. They turned to look at him and their green eyes lit up with surprise.
"Georgie?!" They exclaimed. They looked at William. "Will?" They added. They were looking between them now, bewildered.
"Sam," George said, "what are you doing here?"
Sam's two companions were now using the tarp as a stretcher to carry the body back to the SUV they had arrived in.
"Sam," the first man said, "we could use your help here."
"I-in a minute, Ianto," Sam responded. She reached up to rub her forehead. "Listen," she sighed, "I'd really... really love to stay and talk with you guys, but I have to go. Can I maybe... talk to you later?" She was already walking away.
"Sam!" William called after her.
"Will, please," Sam said, holding out her hand to stop him following, "later." Then she turned and ran after her two friends.
"That was odd." George muttered, watching her go.
"Very odd," William agreed, "something's going on here, and your half-sibling is definitely wrapped up in it somehow."