Disclaimer: I don't own CSI or any of its characters.

Summary: While swing shift has to work on several killings of a serial murderer,

everybody starts to wonder if Greg and Sara are not telling them something. (Sara/Greg)

A/N: Well, the next chapters will probably come out slowly as I'm currently doing an internship full time, so I don't have too much time to write, but the next chapter is almost ready (I hope this doesn't sound like a threat -).

Thanks again to FongSaiYuk319 for beta-reading. Remaining mistakes are mine, as usual. : )

And now I'll be at least so nice to thank all who reviewed: thanks to VeganCSI, Crookedpen, SpeedRacer15, ObessedTWFan, missusmesser, loose-canon-with-a-gun, fartoperfectionand Tripp3235!

Chapter 4 – Co-operate

Warrick flung the crumpled piece of paper into the trash can, which was standing in the break room, and cursed quietly.

Shortly after their pre-shift meeting, when Catherine had told him and Nick that the killer was probably a woman, or more exactly, that probably one of the killers was a woman, they had gotten a call to another crime scene: another shooting, another victim.

He, Catherine, and Nick had examined the crime scene, the case being their top priority now. While they were working there, Catherine had gotten another call about another homicide. She had sent Nick to work on that while she and Warrick finished the scene.

Warrick let himself sink on the couch in the break room. Nick had just returned from his crime scene and reported to Catherine that it was very likely another case in their series of killings.

Sitting down next to Warrick, Nick said, "It's the same like the last cases." Catherine nodded. "Only the first two cases don't really fit."

Warrick frowned. "But Ballistics confirmed that the same weapon was used in all the cases."

"This time the same gun can't have been used," Nick stated. "The shootings happened about the same time, but far away from each other."

When he entered the lab, Greg looked at his watch and saw that he had still more than two hours time until his shift started.

He had decided to come in extra early to help Sara, who had hinted that she would start early. She hoped to finally find a lead in their homicide, always fearing that she would be ordered to work on a new, urgent case, which might have a higher priority, at least a higher priority for the lab. Sara knew that she would never understand why obviously some cases, some victims, were preferred before others.

She had hinted it in the morning when she and Greg had grabbed breakfast together. Greg smiled at the memory.

At the end of their shift, when he had been about to leave, Sara had caught him in the locker room. "Look," she had started, "about tonight…"

Greg had looked at her questioningly.

"…I'm sorry I snapped at you …," Sara had continued, "it was out of line… I –"

Greg had cut her off softly. "It's okay."

But Sara had not finished there.

"You want to grab breakfast?" she had asked quickly.

Greg had opened his mouth, but had not said anything. He had not exactly gotten the opportunity to, as Sara had already continued, "Well, I ate at your place yesterday, so … I thought I could buy this time and -"

"Yeah, sure," Greg had accepted gladly.

Warrick was on his way to the locker room, when he saw Greg in the hallway. "Hey," he called him, "it's still two hours to go until your shift. You're early."

Greg nodded. "Yeah, hot case." He looked around, frowning. "Have you seen Sara?" he wanted to know.

Warrick frowned, too. "Isn't she with you? You're both working this case, aren't you?"

Greg nodded again.

"I saw her shortly before I went with Nick and Catherine to a scene. She was heading to the exit, I called after her, but she didn't hear me, obviously. She left the building and I haven't seen her since," Warrick told Greg, who seemed rather worried.

Warrick looked at his watch. "It was about four hours ago."

Greg took out his cell phone and dialed Sara's number. He listened to the ringing on the other side of the line, pacing some steps up and down in the hallway, Warrick standing next to him, looking concerned.

"Come on, Sar, pick up," Greg muttered. He continued to pace up and down, until he abruptly stopped, when he heard that somebody picked up.

"Sidle."

Greg breathed a sign of relief. "Sara."

"What's up, Greg?" Sara asked calmly.

"Where are you?"

"Uh, it's still time until shift." Sara evaded the question.

"But you're working, aren't you? Where are you?" Greg repeated his query.

Sara hesitated. Greg could hear cars rushing by in the distance.

"I'm back at the scene," Sara started quietly, "I wanted to use the daylight to look for something we might have missed, I've examined every inch of this backyard several times, but –".

She was interrupted by Greg. "I'll come," he said, temporarily refraining from verbalizing any reproaches to Sara for going back to the scene alone.

He turned to go to the locker room to grab his things, when Warrick made him aware of his presence by calling after him. "Where is she?" he wanted to know.

"She's gone back to the scene, alone," Greg stated and looked at Warrick.

"Working overtime again?" Warrick said, although he knew as well as Greg that he wanted to say something else, that he was thinking of something else.

They had seated in a cozy little café not far from the lab.

Sara had bought pancakes and two cups of coffee and had carried it to their table. "Just don't get used to it, Sanders," she had said, winking.

"Used to what?"

"Used to me bringing you breakfast."

"No problem. I can bring it in future, if that is what you want," Greg had returned, grinning.

They had eaten in silence for some minutes, until Greg had broken the quietness by talking about this and that. While he had been talking Sara's expression had changed to a thoughtful one and her eyes seemed absent. Greg had stopped talking in mid-sentence but Sara had not seemed to notice it.

Greg had lowered his head, trying to catch her gaze. "Hey, Sara," he had called, "what are you thinking about?"

Sara had started a little, returning to present place and time.

"Hey, where have you been?" Greg had asked lightly. "You've been thinking about the case?"

Sara nodded. "There has to be something," she had declared in a serious voice. "There have to be at least traces of how she has been brought there," she had said, pondering, referring to the victim that had been found in the alley.

"I don't want it to get a cold case."

"None of us does," Greg had stated earnestly.

When Greg arrived at the scene, the last light of the day had disappeared. It got never really dark in Las Vegas because of all the lights and the street in which Greg had parked the SUV was well lighted, too, but he could not see anything in the alley that let to the crime scene that they had worked on two nights ago.

So he switched on his flashlight and walked along the alleyway and when he was several paces in it, he thought he had seen the shining of another flashlight.

"Sara," he called loudly. Shortly before the end of the alley he stopped and waited. Some seconds later, Sara came around the corner and held her flashlight in his direction, so that he shut his eyes because of the blinding light.

"Greg," said Sara shortly and turned around to return into the backyard again.

Greg approached her and touched her shoulder. "You shouldn't have come here alone, Sara."

Sara walked away from him, so that his hand dropped from her shoulder. Without turning around or looking at him, she mumbled, "You don't have to babysit me, Greg."

"What I don't have to do is tell you how dangerous it is," Greg answered calmly and followed her into the backyard. "Did you even tell Grissom where you were going?" he asked.

"I don't have to tell him, it's my free time, after all." Sara continued to examine the bottom with her flashlight.

Greg sighed. He knew it was pointless to discuss with Sara when she was in a mood like this. Making a last try, he said, "He still wouldn't like it."

Sara turned around abruptly and starred at him. "You won't tell him, will you?" she asked and Greg wondered if it was resignation that he heard in her voice.

Greg shook his head. "I won't."

Approaching her once again, grabbing her left hand – her right arm that held the flashlight hand sunken down and the light was focused on only a single spot on the ground – he said, "But please, don't do these pointless, dangerous actions again. You know very well, that we could've come together bringing a cop with us."

"What I do in my free time-", Sara argued, but she stopped when she saw Greg's expression of concern in the dim light of their flash lights, an expression that told her that he meant it seriously and that he was really worried.

She smiled briefly and squeezed his hand lightly, and then she turned around again and started to examine the walls of the house that they were standing behind by letting the light of her flashlight wander along the walls.

"Do you think that there is a point in doing this?" Greg asked, but began to do the same like Sara.

"There has to be something," she answered. Suddenly she stopped her flashlight at a spot on the wall in front of them where there was a dark substance. Sara starred at the spot that was about three feet above her head.

Then she walked to her kit, which stood some paces next to her, and opened it. She put on gloves and brought out something that Greg recognized as luminol.

Sara walked back to the wall, pointed her light again on the spot and looked up. Then she turned to Greg and asked, "Would you help me, please?"

Greg starred for a moment, wondering what she was talking about. Then she pointed to the spot above and he understood.

He folded his hands and held them in such a way that Sara could step onto them. She put one of her feet carefully onto his hands and lifted herself upwards, using his hands as a ladder. She balanced and leaned against the wall slightly with one hand. Now her head was only a little length under the spot with the dark substance.

Sara sprayed the spot with luminal. Greg could see the glazing on the wall.

"It's blood," Sara confirmed. "Let me down, please."

She stepped back onto the ground and Greg grabbed her lightly to help her keeping the balance, finally letting reluctantly go of her.

Sara walked once again to her kit. When she returned, she smiled at Greg. "Another go?" she asked, pointing on the wall. "I want to take a DNA sample."

Greg nodded, grinning. "Sure."

TBC