Disclaimer: The mah-ve-lous Dick Wolf created the characters. I just play with them.

Author's note: I have a soft spot for the detectives' demonstrations.

"You be the vic," Olivia says.

"'Kay," Elliot answers, moving into position.

"Alright, so our witness says she saw our vic looking out the window into another apartment."

"Right," Elliot agrees. "We assume he was gettin' off peepin' on a neighbor."

"Explains the fluids," Olivia adds.

"Mm-hm." Elliot stands in front of the window, looking at the building across the street.

"Okay, then the witness says someone came up behind him," Olivia steps behind Elliot," reaches up to grab the cord from the blinds…" she stops as she's reaching for the cord.

"What's wrong?" Elliot asks, peering over his shoulder.

"Hmm…our witness said the perp reached up for the cord, but if the blinds were already open—"

"—then our doer wouldn't have to reach up," Elliot finished. He pursed his lips in thought, then said, "Do you think our witness is lying?"

Olivia shrugged. "Why would she? Maybe she just meant to say the perp reached over."

"Alright, we'll just assume it's a mistake for now," Elliot concedes, turning back to the window.

So the perp grabs the cord and wraps it around our guy's neck," Olivia continues, taking the cord and quickly bringing it around her partner's neck, but letting it go slack.

"Our guy struggles, reaches behind him to try and throw off the attacker…" Elliot mimics, grasping at Olivia's hands, then stops midway through a swipe.

"What?" Olivia asks, unwinding the loose cord from around her partner's neck as he turns around to face her.

"Our witness had bandages on her hands where the vic would've scratched."

"Huh…" was all Olivia had to say to that.

"Still think our witness was 'mistaken'?"

Olivia wasn't listening, though. Her head is tilted to the side, studying Elliot's neck.

"Liv?"

"I left a mark with the cord. Right there." She traces the line lightly with her index finger across the right side of his throat, angled down from the jaw line.

Trying to ignore the tingling sensation left behind from her touch, he says, "Well, I'm sure it'll disappear in a few..." his brow furrows "…oh." He reaches into his blazer pocket to pull out the photo of their victim. He traces the red welt on the photo going from the Anthony Cooper's left jaw line. "It's the wrong side."

"Yeah," says Olivia, chewing her lower lip in thought.

Elliot shrugs. "Alright, so our guy was facing his attacker like we are right now."

Olivia shakes her head. "Okay, but what about the semen?"

He opens his mouth to reply, then closes it and shakes his head, shrugging his shoulders again. "I don't know, Liv."

But at that moment, Olivia got a look of realization on her face. "I think I do."

She steps around Elliot and tugs his arm to get him to face her. Olivia steps all the way back until her heel hits the wall, then says, "Doc Warner said our perp is a woman, right? Based on the DNA from the epithelials on the cord."

Elliot nods. "Right."

"I don't think Anthony Cooper was masturbating before he died. I think he had sex before he died."

"Okay, I see where you're going with this," Elliot replies, stepping forward so that he is mere inches from his partner. "Your theory is flawed, though. Unless your doer is a tall woman—which our unreliable witness is not—then she couldn't reach the cord over this bookshelf."

She gave Elliot a funny look. "Boost me up, Elliot."

"Boost…but why would the victim willingly boost up the perp so that she can reach the cord she's about to strangle—what's funny?"

Olivia was chuckling at his misunderstanding. "I'm sorry, it's just…I assumed you knew that sex up against the wall is easier when the woman is sitting on the guy's hips."

There's an awkward pause as Elliot processes the information. He clears his throat uncomfortably, then steps forward again. "Okay, so he…gives her a boost." Elliot places his hands gingerly on the back of Olivia's thighs, then pulls her up to rest on his pelvic bone. She wraps her legs around his waist and her arms around his shoulders to gain leverage while she wriggles to adjust. He looks at the ceiling and unconsciously applies pressure to her thighs, making a slight grunting noise as he wills himself not to be affected by her movement.

She stops at the sound and says, "Uh…sorry."

He moves forward more so that his partner is firmly pinned against the wall. She squirms a little more, then relaxes against his hips and the wall.

"You comfortable?" he asks in a pinched voice.

She grins mischievously and brushes the tips of her nails over the day-old stubble on his set jaw. She wriggles a little more, then says, "Yes."

"Are you sure?" he asks in a voice like sex dipped in chocolate, while his hands slide slowly up from her thighs to cradle her behind, and he presses her more firmly into the wall.

"Uh…" Olivia says, her breathing picking up and her nails now digging into his shoulders, "yeah. I'm good."

"Good," he says in his usual gravelly voice, "then let's continue with the walk-through."

She lets out her breath in a whoosh and lays her head against the wall for a moment, then easily reaches over the bookshelf and finds the cord. She pulls it, but instead of wrapping it around his neck, she dangles it in front of his face. "Looks like my theory checks out."

He rolls his eyes and sets her back on the floor.

It helps to walk these things through.