"So basically what you're saying is that not a single one of those samples yielded anything helpful?" Nick sounded frustrated. He had hoped that at least one of the DNA samples they'd collected at the scene and off of the victim's body would give them something.

"I suppose it all depends on your perspective." Greg was trying to stay optimistic, if for no other reason than to keep his own spirits up while helping with this case.

Nick looked at Greg with a hint of annoyance on his face.

Greg continued. "We know that there was more than one perpetrator and that they were both male."

Nick exhaled loudly. "All we can prove is that two guys were in the house and that one of them pissed the cat off enough to get a nasty scratch. Without any DNA on the victim's body, and without being able to identify who the donors are, we have nothing."

When Nick and Sara had briefed Grissom on what they had found, he had pointed out that although they had DNA from the cat's claws it did not necessarily prove that they belonged to the killer of their victim 27 year old Jenna Matthews, only the likely killer of the cat. They needed something more concrete to go on that would stand up in court, provided they could identify the mystery DNA donors.

"Hey, guys." Sara walked into the DNA lab with an expectant expression.

Nick and Greg both looked up.

She held up a knife in an evidence bag as a smug smile spread across her face. "Look what I found."

Nick furrowed his brow as he looked at her. "We didn't find a knife when we processed the house."

"I went back to the scene." Her tone was defensive.

Nick's protective instinct immediately kicked in as he raised an eyebrow. "Alone?" He didn't like the idea of Sara Sidle, or any other woman for that matter, wandering around a crime scene by herself in the middle of the night, armed or not. It certainly hadn't helped Holly Gribbs any.

Sara clenched her jaw as she looked at him, not bothering to answer his question. She could tell by the tone in his voice that regardless of the possible implications that the knife held for their case that he was not happy with her for going back to the scene alone. "It was in the bushes outside the back door. It's positive for traces of human blood."

Nick raised both brows at her.

"Let's see if there's any DNA." Greg ignored the tension between Nick and Sara and reached for the bag so he could swab it for any traces of DNA.

Sara glanced at Greg and pursed her lips. "Thanks." She gave Nick a pointed stare and then headed back down the hall to the layout room. She knew that Nick had a valid concern, but she didn't really want to deal with it at the moment. She settled herself back in the layout room, studying the crime scene photos as she mulled over possible scenarios.

Nick cleared his throat as he entered the room a few minutes later. "Sara." His tone was soft, cautious.

She didn't glance up. "I don't want a lecture."

He settled himself in a chair next to her, glancing over at her before speaking again. "I just worry that's all. It's not a commentary on your skills as a CSI."

She let out a deep breath before looking over at him. "Then why is everyone being so damn protective lately?"

Nick furrowed his brow at her. "I didn't think we were." He didn't think he was treating her any differently that he'd ever treated her before.

She looked at him doubtfully. "Admit it Nick, ever since I got a gun pulled on me back in May, you've all been a little extra protective." She gave him a pointed stare. "You in particular." She turned back to the photos, hoping that Nick would drop the subject. She didn't want to be reminded of the instance where she and Detective Vartan had a suspect pull a gun on them while they were investigating a bizarre murder case. It had served to remind her of her own mortality in a much too real way.

He thought about her statement for a long moment before answering her. "Can I help it if I care about you?" Of all the CSIs, Nick tended to wear his heart on his sleeve. He and Sara had become close over the course of the last four years, and the thought of something bad happening to her bothered him a great deal.

Sara wasn't sure how to respond to his comment. She knew that he cared, he showed that he cared, but sometimes she wasn't sure how much he cared, and that made her nervous.

"I just don't want something to happen to you." There was something in the tone of his voice that implied that there was more behind it than he was willing to tell her.

She glanced up at him. "Nothing is going to happen to me." Her expression implored him to believe her, but there was an edge of fear in her eyes that he was toeing across an unspoken line set between them that she wasn't sure she wanted to cross; especially after the heartbreak that she'd experienced from allowing herself to feel something for Grissom. She'd finally gotten over that and she wasn't sure she was ready to entangle her emotions in someone else for a while.

Nick let out a frustrated sigh. "Sara, I know you think you're indestructible, but you're not."

She shook her head in protest. "No, you don't get it, Nick. I know that I'm not, I know that. But I can't let it stop me from doing my job either."

Nick knew that if he wasn't careful, they were going to be in the middle of a full blown argument, likely fuelled more by their frustration about the case than about what they were talking about, and that wouldn't help them find their victim's killer any faster. He paused and thought for a moment before responding. "I'm sorry."

Sara had been gearing herself to defend her position; his apology had been unexpected and his soft tone had thrown her off a bit.

He smiled. "I'm sorry if I overreacted." His smile turned into a smirk. "I just would hate for something to happen to my favorite CSI." His attempt to lighten the moment didn't belie the concern he felt, but he knew that if he kept pressing the issue that she'd just shut him out.

Sara couldn't help the chuckle that escaped her lips as she pursed them together. She glanced over at him and a hint of a smile pulled at the corners of her mouth. "So I'm your favorite, huh?" Her tone was both teasing and smug.

Nick replied in a flirtatious banter. "Well, now that you mention it."

Sara was about to say something in response when something in one of the crime scene photos caught her eye. "Nick." She pointed at the photo. "What do you see?"

"Is this a trick question?" He glanced at her momentarily and then he looked at the photo while his mind shifted gears, trying to see what she was seeing. He looked back at her with curiosity. "Help me out here."

She looked at him intently. "What's the first thing you do when you're getting ready to go on a trip?"

"Laundry." Nick smirked.

Sara rolled her eyes and continued. "According to her coworkers at Megasoft she was supposed to be going on a romantic vacation to Jamaica with her boyfriend, but there are no suitcases packed, no plane tickets, and no passport."

Nick nodded, locking eyes with her. "And no boyfriend."