Sherlock had his eye pressed to the microscope, looking at the blood sample, when he heard the noise. He sighed, just what he needed. Someone was coming in and disturbing him from his work.

'Go away. I'm busy' he called out without looking up from his work.

'Sherlock, we need to talk.' Lestrade's voice cut over Sherlock's forcing him to move away from the microscope. 'Are you, or are you not continuing with this case? I know Anderson was being unreasonable, and I have told him that. Will you continue? You said you knew who the murderer was.'

'Of course I'm continuing the case, Lestrade. I haven't had so much fun in ages. I didn't even need Anderson's statement anyway. It doesn't make a jot of difference. I got what I needed from him, and that was to look at his hands and arms. However, I would appreciate it, if you don't tell Anderson that I'm continuing his case. Let him stew awhile.' Lestrade nodded, that was fair and he was just glad that Sherlock was continuing the case. 'As to knowing who the murderer is, I never said that. What I said was that Anderson was innocent. I would know who the murderer is by now, but you interrupted me just as I was finding out.' Sherlock looked at Lestrade accusingly, and he had the grace to look guilty.

'Oh, right. I'll just let you get on with it then. But you know how you asked earlier who Martin worked for before? Well, no one. He had an offer from someone called Jim, but he turned it down and joined us. Anyway, just say if you need anything else. I'll be at the station.'

Sherlock didn't even reply. He just went back to his microscope and blood samples from the pen, considering Lestrade's words. Jim. Where had he heard that name before, and could it be connected to this murder? He shrugged, there were more pressing things at hand. The results had just come in from the blood on the pen. There was a match. Richard Hill. Professional assassin. Wanted by police in four countries including Britain and France. Also known as Monsieur Petit. 14 assumed murders, but no evidence.

Sherlock grinned. He had a name, and all the information seemed to fit the case perfectly. Now, he just needed the man. But how had the blood gotten onto the pen in the first place? Sherlock leaned back in his chair and started to reconstruct the murder in his mind.

3.30am. Rob Martin was engrossed in his work and editing his report after a breakthrough. He didn't notice a man creep into his room, probably assuming it was a cleaner. The assassin, Richard Hill, grabbed him around the neck from behind and started strangling. Martin had been working on the page John found when he died. As an automatic reaction, he chucked it away, and it landed under the desk. Richard Hill didn't notice. Martin's second reaction was defence. He stabbed upwards at Hill's arms with the item he already held in his hand. He pierced through the skin with the red pen. That's where the blood came from. It caused Richard Hill to lose his grip. Rob continued to fight back, but the longer Hill held on, the weaker he got. Eventually the pen stopped piercing the skin. Martin died, and was dragged to the janitor's closet. But why…?

Sherlock sat up suddenly. He had an idea, but he needed several things before he could make it work. He grabbed his phone and sent John a quick text. Case almost complete. I need to check one more thing. Don't stay up for me. I will be back late. Be ready for grand finale tomorrow. -S