He should have been happy. After all, he'd just been proven innocent in Benedict's death and the real murderer was dead. Sure, one scumbag had managed to get out of the country and escape proper punishment, but, all things considered, this had been a good day.

So why did Tim look as though he was still on the hook for shooting a cop?

Everyone else had already gone. Tony was still smarting from his ordeal with the sperm bank. Ziva, taking pity on him (and feeling a little guilty for snooping), offered to buy him a drink and Abby was all too pleased to join them. Even Ducky and Jimmy had accepted invitations for an evening stop at the bar. This case had hit too close to home; they all needed a little relaxation.

It was no surprise that Gibbs hadn't tagged along, but Tim's declination was one. Though he wasn't much of a drinker, Tim rarely turned down their invitations. When he did, it meant something was troubling him. After everything that had happened in the past few days, it was obvious what that something was.

Even if he didn't want to go out with the others, there was no reason for Tim to be at the office. His report had been submitted, he no longer was in custody, and there were no cases for him to work that night. And yet, Gibbs watched as Tim sat at his desk, head hanging down as he looked over the papers on his desk. Gibbs had a pretty good idea what he was looking at.

"Abby told me her tests were inconclusive."

Tim looked up with a frown. "What?"

"The tests to determine which bullet killed him."

"Oh." His eyes flickered back down. "Yeah…she told me it would be impossible to tell."

"And what do you think of that?"

He shrugged. "If she can't tell, she can't tell. Nothing more she can do."

"Is that why you've been staring at her report for the past hour instead of going home?"

Tim was visibly embarrassed about having been caught, but he made no attempts to deny it. Why bother? Gibbs would see right through that. "I just thought some fresh eyes may help."

"Help what?"

"Help figure out what happened."

"We know what happened, McGee. Archer was a dirty cop. Benedict confronted him and you were unlucky enough to stumble upon it. The rest doesn't matter."

His head snapped up and Tim looked mortified. "Doesn't matter? A cop was killed and it doesn't matter?"

"That's not what I meant," Gibbs said. He sighed and massaged his temples. Even he was starting to feel the effects of the case. "The bad guy is dead, you've been exonerated, and Metro is off our backs. We can't change what already happened, but we can keep it from affecting us."

But Tim didn't agree. "Boss, I shot a man. I shot a cop. How can that not affect me?"

"You reacted as you were trained to, McGee."

"It doesn't change the fact that I ki—" He stopped abruptly and looked away abashedly. "The fact that I shot him while he was trying to make an arrest."

"Why does it matter?"

"What?"

"Why does it matter?" Gibbs repeated slowly. "Benedict is dead and nothing you do—no amount of worrying and obsessing over it—is going to change that. So why does it matter who fired the kill shot?"

Tim shot to his feet. "Because I have to know!" His exclamation came in a louder tone than he'd anticipated and more than a few of the late night stragglers turned and looked at him with curiosity. As he slunk back into his chair, he wondered how many of them knew he'd shot a cop.

"Will knowing make you feel any better?"

"If I know I'm not responsible for his death? Yeah, I'd say that would make me feel better."

Gibbs studied him in silence, his eyes squinted slightly as though he were trying to peer into Tim's mind. He stood and strode around to Tim's desk and leaned in, placing his hands atop the desk to hold him up. "I don't believe that."

Tim pressed himself back in his chair, squirming beneath the stare. "You don't?"

"No, McGee; I think that no matter what Abby had told you, you would have found some way to blame yourself for the death. You distracted Benedict so he didn't see the shot coming. You scared Archer into shooting. Anything."

"Why would I do that?"

"Because you feel guilty for what happened, no matter what part you played in his death. Because you have a sensitive heart, McGee, and you're the type to overanalyze yourself, almost to the point of obsession. Because you were told by others that you were at fault, and now you've convinced yourself that it's true."

Now it was Tim's turn to be silent. He averted his gaze sat there, not sure of which words to use. How could he possibly put into words how he felt?

"I almost didn't shoot," he said. "A split second after I heard the shot…I didn't want to pull the trigger. I don't even remember doing it. I just remember seeing the flashes from my gun and seeing him fall as the SUV drove off."

"But you did shoot. You're an agent. You did what you had to do."

Tim leaned forward and rested his forehead in his open palm. "I just want to know one way or another. Even if I find another way to blame myself. I just have to know which shot killed him."

"Have you tried looking at this more logically?"

"What do you mean?"

"Come on, McGee. You're supposed to be the science guy here, the one who breaks down a situation to its barest form and studies it. Look at it this way: how close were you to Benedict?"

"Uh, a good thirty feet away.'

"And how close was Archer?"

"Five or so feet."

"Were you shooting to kill?"

Tim winced. "No…no, I just wanted to disarm him and make sure he didn't shoot back."

"What about Archer? You think he was just trying to hurt Benedict long enough to get away? Or do you think his intention was to kill him so he'd never be able to tell what he'd seen?"

"I guess he was trying to kill him." But there was no guess about it; Archer hadn't been above murder to get what he wanted. He was prepared to kill anyone who got in his way, including his own partner.

Gibbs nodded. "So two men shot at Benedict. One of you was standing at least thirty feet away and wasn't trying to kill him; the other was no more than five feet away and had no intention of leaving behind a witness. Tell me, if you were serving on a jury, which one would you suspect?"

When it was put like that, Tim had to admit all signs pointed to Archer. "But wouldn't it bother you? Never knowing for certain?"

"McGee, life is full of uncertainty. There will always be suspicions and doubts, especially in our line of work. You can't let it tear you up. If you do, you won't last long."

"Are you saying I'm not cut out for this job?"

Gibbs couldn't help but smile. "If I thought you weren't cut out for this job, you'd be out on your ass instead of sitting here, going over this ballistics report for what has to be the fifth time today."

He gently took the report and pulled it away, tucking it into a folder and locking it in his desk drawer. "Now I am ordering you to go home. Get some sleep."

Tim knew better than to argue, so he began gathering his things, though he still looked troubled. Every agent had that one case that would always stick with them, gnawing at conscience, regardless of whether or not it was ever resolved. Gibbs could see that this would be Tim's.

"McGee."

Tim stopped and turned, looking over his shoulder expectantly. "Yeah, boss?"

"It's okay to want answers. It's okay if the cases get to you now and then; it just means you're human. To be honest, I don't want to see the day that you can go through something like this and walk away from it unaffected. But at some point you've got to lock it away."

"And if I can't?"

"You will, McGee. You will."

"How can you be sure?"

He gave Tim a gentle pat on the back. "Because I've been there. Because I know what you're capable of. You may not have the training and experience that me, Tony, and Ziva have, but you're just as strong as the rest of us; you just have a different way of dealing with things."

"Maybe I should start building a boat in my basement." he quipped, trying to lighten the mood. Gibbs responded with a not-quite-withering glare, hiding the small smile that was pushing to escape.

"I think you should do whatever it takes to get your mind off of the job. You see enough of it here; don't take it home with you."

Tim nodded solemnly, though he couldn't make any promises. The last couple of nights had been filled with dreams of that night and he had a feeling that night wouldn't be any different. Still, that didn't mean he couldn't try to get through this with the support of friends.

"Maybe I will grab a drink at the bar," he said as he pulled out his phone. "Tony even offered to treat me. Of course, that's probably because Ziva offered to treat him for some reason, but it's still strange for him."

Gibbs nodded. "Do that, McGee. I think it'll help."

"You want to come, boss?"

"I'll pass this time. Too much to get done here."

It was on the tip of his tongue to point out the hypocrisy of Gibbs' actions after everything he'd just said. But he thought better of it. This was just Gibbs' way of dealing with things. "Okay…I guess I'll see you on Monday."

"Monday," Gibbs replied affirmatively. He watched Tim leave, feeling a mixture of pride and sadness. Despite his anger upon seeing Tim freeze up at Archer's house, Gibbs couldn't be prouder of the man, of the way he'd handled himself throughout this ordeal. And yet, he knew that look of dejection. It marked the beginning of Tim's real education into the world of law enforcement, that seldom talked of state of mind, filled with guilt and pain.

And that never-ending cycle of uncertainty.

AN: I wrote this because I felt like "Probie" ended a little too soon. Thank you for reading :)