Title: The Unknown Threat

Disclaimer: I do not own Criminal Minds

Summary: A new danger in closing in on one of their own. While investigating a new string of deaths, truths with come out. Sequel to "The Mysterious Dr. Reid" and "Physics Magic…Bullet".

A/N: For this story, does anyone mind if we just say that Ashley was called away for a spur of the moment transfer and JJ is on her way back in? Let's just roll with it.

Thanks to everyone who has liked this series! Gotten tons of requests to continue it. Sorry I have been away for so long. I don't think I have uploaded since July. I'm a med student, so life is kind of hectic as you can guess. I was holding back publishing this because I only have two chapters written. That being said, updates will probably take a while. I'll shoot for once a week right now. Thanks again for reading, hope you enjoy. Please R&R.

Chapter 1

Previously in "Physics Magic…Bullet"

A muscular man with grey peppered hair stood watching the team of profilers leaving the building through binoculars on a nearby rooftop. He wore a black suit that would not have looked out of place within the building itself. He sighed as he remembered the details of his objective. Again he looked at the team as they got into two black SUVs. The last to get in was his true target: a tall, thin, young man with brown hair…his name was Dr. Spencer Reid.

Now:

The scene that spread before the team was a brutal one. They entered the old apartment building through the narrow entrance. The blood trail started in the hallway beside a sting of mail boxes while smears along the wall and droplets on the floor extended to apartment 1D toward the back. Crossing the threshold of the apartment, their senses were met with the overwhelming metallic smell of blood. The living room was small as they piled in with the CSU and officers on scene. Red covered most of the surfaces of the room.

"Agent Hotchner," a shorter man acknowledged him with a firm handshake, "Thank you for coming so quickly. As you can tell, this is really brutal. We don't see them like this very often."

"Thank you for calling us in, Detective Bereze. What can you tell us?" Hotch replied. He didn't know much on the details on such short notice, only that the local senior homicide detective had called asking for help after two murders.

"Well, unfortunately not much. The victim here is believed to be the renter, a 43 year old white male named Dr. Jeremiah Welch," Bereze answered.

"Believed to be?" Morgan asked.

"Uh…there is not much left of the body. Probably going to need dentals to officially identify him." The man gestured toward behind the couch. The team moved around to get a view and were met with a truly gruesome site.

The man had clearly been beaten to death. His entire face and body were swollen and marked with cuts. He looked unrecognizable as his eyes were swollen over completely. Reid crouched next to the dead man.

"Looks like he was struck repeatedly with a sharp hard object." Reid's gazed continued to comb the body, "Based on the pattern of the marks, its looks like brass knuckles."

"That's what our guys thought too. Poor guy got jumped coming in the main building door, likely tried to escape to his apartment. The beating continued here."

Rossi spoke up from the other side of the room, "He was waiting for the victim to come in."

"That combined with the ferocity of the beating indicates he was targeted specifically. This was personal," Prentiss offered.

Blood was literally dripping down the curtains.

Hotch moved his eyes from the mangled body back to the detective, "What did this man do for a living?"

"Believe it or not he was a professor at Georgetown; physics department. Apparently he was well-liked on campus and is active in quite a few clubs."

The team let this detail sink in. It was Morgan that asked the most obvious question, "How does a physics professor piss someone off this bad?"

"We haven't got a clue. Talked to the neighbors. They all say that he was a friendly guy; kept to himself a lot. Worked long hours at school and often came home and worked some more. Not many visitors through," Bereze responded.

Reid stood over the body, talking as he thought. "It takes a lot of strength to actually beat someone to death, even with the knuckles. And if you look at the marks on the body, these marks here," he gestured toward the left shoulder exposed through the ripped shirt, "there is more stress on the left side of the mark. While on the face here there is more stress on the right knuckle."

"There were two assailants," Rossi stated.

"Makes sense," Prentiss added. "This was fast and brutal. It would have taken two people to do this and get out before anyone could even figure out what was happening."

Morgan looked at Bereze, "Did the neighbors hear anything? This would have caused a hell of a racket."

"No, it's a quiet building in general. This is a back hallway, helped to muffle the sound a bit. The guys were in and out before anyone in the building even registered something was wrong. The older lady in 1B heard the main door slam and came out to find the blood. She was the one to call the police."

Hotch remembered the original phone conversation, "Did you say there was another victim?"

Bereze nodded, "We had another body a few months ago. A former marine that was running a basketball program at the local community center. He was stabbed 12 times one night after-hours at the center."

"What makes you think they were related?" Morgan asked.

Bereze, who was still wearing gloves made his way over to the body. He pulled up the tattered edge of the professor's shirt to reveal something cut into the skin. "They both had one of these marks."

Rossi squinted from across the room, "What is that?"

Reid answered, "It's the symbol for infinity."

So there is the first chapter. Hope to give you guys something soon. In the mean time, remember to check out the prequels to this if you haven't already. Please R&R and I'll try to give a shout out. You guys are amazing!