When John entered the building he went straight to the janitor's closet, but to his surprise, Sherlock wasn't there. He looked around, puzzled. Sherlock always started by looking at the scene and then the body, so that no one else had time to disturb any evidence. It seemed to John, that Sherlock was so keen to discredit Anderson, he was breaking his own protocol and was biased before he even began to investigate. Sherlock had always maintained that he kept all options open, and considered all possibilities. Apparently, not this time.

John headed back down the elevator, wondering if there would be a taxi that he could take to the morgue, and hopefully to Sherlock. But, as he stepped out of the elevator, something was suddenley shoved into his chest. John looked up, prepared for anything, but to his relief it was just Sherlock looking down at him impatiently.

'What took you so long?' Sherlock asked in an annoyed tone. 'I need you to hold this while I do something.' John looked down at the object in his hands, and recognised it as a tape measure. He held it steady as Sherlock measured the distance between the lift and the carpark that was just outside the front doors.

'30 meters John! Remember that for me', called Sherlock as he re-entered the building. John nodded, pleased that Sherlock was trusting him, but knowing that Sherlock would remember the distance far better than himself.

The pair went up to the third floor, where both the janitor's closet, and Rob Martin's desk were situated. Sherlock took some more, seemingly irrelevant measurements. 45 meters from the janitor's closet to the office. 10 meters from the office to the lift entrance.

'Interesting' muttered Sherlock to himself, 'either our murderer is not the sharpest tool in the shed, or he is very, very cunning.' John was baffled by Sherlock's actions. Rob Martin had been killed in his office, and hidden in closet. That much was hardly suspicious. It seemed the logical thing to do.

Sherlock then continued his investigation with the janitor's closet, which seemed to be exactly how Sherlock had expected. He spent only 10 minutes going over it, collecting just a scrap of cloth, a swab from some spilt cleaning products that were on the floor and a half empty bottle of bleach. There was only a little disturbance in the closet, as the body had been hidden in it, not killed.

'Nothing else of interest here' Sherlock remarked to John, 'time to head to Rob's office, don't you think?'

Lestrade was waiting for them when they entered Rob's old office, which consisted of a desk, a plush chair and a large filing cabinet, that was unlocked.

'Any ideas?' asked Lestrade hopefully, despite knowing full well that Sherlock never said anything unless he was ready.

'Seven. But I need to check a few things before I can prove or reject them. Now, are any documents missing from that filing cabinet, what was the latest case Martin was working on, where did he work before here, and I want to talk to cleaners and anyone else who was here last night.' Lestrade frowned.

'Seven ideas? That seems like a lot. Shouldn't you narrow it down a little? I can have some people check the filing cabinet, but there is no sure way of knowing exactly what should have been in there. The latest case I can help you with. It's a stock standard murder and Martin was in the middle of investigating it. I can get you the brief and his notes on it later. No one was here last night, even the cleaners have corroborated alibis. Furthermore no one was supposed to be here last night. It's not unusual for someone to pull an all-nighter working on a case, but Martin shouldn't have needed to do it, because his case was so simple.'

'Thank you Lestrade. That will be all for now.'

Sherlock immediately set about inspecting every inch of the office, while Lestrade cleared everyone out, so that Sherlock could have a free space. Firstly, Sherlock checked the filing cabinet, but there were no signs that someone had forced their way in, or had looked at any files. There were no footprints on the ground, the chair provided no clues and neither did the walls, door or window. Clearly the murderer had just walked right in without having to force anything.

The desk, however was another matter. Martin was clearly not a tidy man, his desk was cluttered and messy, but there was a blank spot in the middle, where you would normally do your work.

'Well John, Martin was clearly doing some paperwork when he died. Something to do with his case? Probably. Are the papers still here? Doubtful. Help me find them, but don't touch anything if you can avoid it!' John nodded, and together they scoured the room for a sign of the missing papers.

'Aha!' exclaimed Sherlock suddenly. John rushed to his side, only to find his friend clutching a plain, red ballpoint pen. It had been found on the edge of the desk, blending in with the mess. However, Sherlock's eagle eyes had spotted the bloodstains on the pen that were camouflaged by the red colouring. Sherlock bagged the pen, as he clearly thought it would shed some light on the case. John wasn't so sure, but he knew better than to question his friend.

John kept looking for the elusive paper, because Sherlock seemed convinced that the murderer had left at least one page behind. Half an hour later, his patience was rewarded, when John emerged from under the desk with a wrinkled piece of paper in his hand. Sherlock quickly searched under the desk, but no other paper could be found. Lestrade arrived moments later, and both John and Sherlock headed to the jail to talk to Anderson, who was still the only suspect for the murder.