Author's note: This is an idea I had ages ago, but have only just got around to writing because my friends and I had a challenge to post before midnight ages ago and I only made it with twenty minutes to spare. I have now re-read this chapter and corrected any mistakes I may have made and anything I might have forgotten in my struggle to finish before the deadline. Please enjoy - we're going to introduce the crime scenes first, focusing on the CSIs, then the Harry Potter part later on :)

Disclaimer: I don't own either Harry Potter or CSI NY.

Chapter 1:

Early morning sunlight reflected off of the plain glass windows of shops lining an ordinary street in London. The early morning shoppers had begun to crowd the street, exchanging pleasantries and commenting on the latest fashions that lined the shop windows or the quality of the bakery's fresh loaves. Everything was perfectly normal until-

"TRAITOR!"

The cry rang out through the tightly packed street. From every direction, people turned to stare at the two men, dressed strangely in dark robes and cloaks. When compared to the coats and trousers of most of the people in the street with them, the pair looked highly out of place.

The two looked exact opposites of each other, in both size and expression. One, a tall lean man with a crop of shoulder length black hair had backed the other, a rather short, plump man with short mousy curls into the corner of the street. His expression was livid as he threatened the cowering man before him, pointing what appeared to be a wooden stick to his throat.

But then, the shorter man raised his voice:

"First Lily and James and now me! What did I ever do to you Sirius?"

"WHAT DID YOU DO?" the other man, Sirius roared. "DO YOU NEED ME TO SPELL IT OUT FOR YOU?" pushing the other man further against the wall. "YOU ALWAYS WERE A COWARD PETER!"

"I did nothing Sirius," Peter squeaked, though still loud enough for the growing crowd to hear. "It was you! How could you?"

The rest happened too quickly for anyone to react. Sirius let out a growl of anger and

a second later the air was filled with dust... shouts... rubble.

Sirius turned on the spot, trying to survey the scene before him but only managing to catch glimpses of the terrified crowd. His confusion then dissipated as he realised what had happened.

Among the cries of the injured crowd, the laughter could be heard, echoing from his throat.

He heard a dozen cracks and felt the pressure of two pairs of hands on his arms, he allowed himself to be held in place, not having enough energy to try and stop them. Tricked. All of them. By Peter Pettigrew, whom no one would have suspected of anything. Sirius continued to laugh at how stupid they had all been to not realise...And to think that he had suspected Remus...

As the dust began to settle at his feet, Sirius could see the scene unfolding around them. He stood in a crater, surrounded by Magical Law Enforcement Squad, recognisable by their Ministry uniforms. The pavement and road had been blown to pieces, cracking the sewers open and causing the stench of sewage to mingle with the smell of blood in the air.

Before him lay a bundle of rags, formerly robes, covered with blood and dirt. To anyone else, this may have caused them to sober immediately, but Sirius just continued to laugh at the simplicity of Peter's plan, and yet how brilliantly he had had them all fooled.

Further from him, he saw the bodies of Muggles lying on the floor with others standing over them, crying, shouting or trying to offer whatever help they could.

Before he could take a full look and really take in the gravity of what had happened, a short, slightly portly man stepped in front of him. He looked slightly ill, taking nervous glances at the people around them and occasionally at the pile of clothes to Sirius' right.

"Sirius Black," he said, sounding as though keeping composed was taking all of his energy. "I, Cornelius Fudge, arrest you for the murders of Wizard, Peter Pettigrew and twelve muggles. There will be no need for you to say anything."

And with that, Fudge indicated to the two wizards holding Sirius to take him away, with a nod of his head. He then turned to another and said:

"You know what to do; take statements then wipe their memories. They shouldn't have to remember this."

Sirius took one last look at the crowd of muggles and the open sewer before the whole scene vanished.

That was when the sound of the sirens began to reverberate through the polluted air.

OoOoO

"Mac!"

"What have we got, Flack?" asked Mac Taylor as he ducked under the yellow tape barrier that had already been put up in order to keep the scene from the prying eyes of the public. He turned to Don Flack as they began to walk down towards the centre of the street.

"Witness called it in whilst it was happening; two men over on that side of the street shouting at the top of their voices, crowd gathered around the edge watching. The explosion ripped the street apart, taking the sewer with it," Flack explained to Mac from the notes scrawled hastily on his pad.

"And where is our witness now?" Mac asked as they passed a few other cops headed in the direction they had previously come.

"Dead. Part of the front of the crowd that got caught in the explosion. We've got thirteen deceased in total, but only twelve bodies," Flack finished, turning to Mac as they came to a stop in front of Hawkes who stood as they approached. Mac's face turned to one of confusion.

"I might be able to help with that," he said moving to join them. "Though I've got queries about it too. There is a pile of blood splattered clothes on the floor with the only recognisable body part being the right index finger on the floor. But other than that there is no blood splatter on the walls or floor or anywhere else to be honest. No evidence to show there was anyone stood there at all. It just doesn't seem to fit with a typical explosion that you usually find. All the other bodies have minimal trace, mainly hit by rubble from the street. But I'm not sure what was used here," Hawkes concluded as Mac looked at the variety of surfaces that were covered in dust and shards of the shattered street.

"What about the man they caught?" Mac asked the cop and the former pathologist. "With this many witnesses surely there is no way they can't convict him?"

"The guy's pleading that he's innocent. He was taken away by a specialist group right after the explosion. Our guys arrived on the scene about ten minutes later so we haven't been able to hear his side of the tale yet, but it definitely seems to be worth investigating, Mac."

"Alright" Mac responded, clearing surmising that that was all the information he was going to get out of his detective. "Sheldon, get the bodies to Sid; see if he can make anything else out that you might have missed."

"Yes Boss," Hawkes replied, jogging over to the team moving the stretchers into the van.

As Hawkes left, Lindsay Messer walked over to the head of the crime lab, camera in hand.

"Mac- I've marked up and photographed the initial findings, but it's going to take a while to sort through all this to find what's really important here," she told him, with a slight grimace.

"Take as long as you need Lindsay and I'll find some extra people to try and help you - sounds as though you're going to need them," Mac replied to her. She nodded and moved away towards the crater in the street.

Once Lindsay had gone, Mac continued to talk to Flack-

"Flack, come with me, we're going to find out more about the man who blew these people away."

A/N: Cue 'Baba O'Reily' by The Who. Please review- It is much appreciated :) Thanks!