Murder of a Cryptologist

Question

Your friend, the Cryptologist Mr. Toboggan, has been murdered in his house. You being a detective and a Cryptologist yourself have been asked to lend a hand in solving the murder.

You arrive at the murder scene and find it in complete disarray. The body is on the floor next to his computer table. The laptop is open and there are various open windows. One of them is showing the map of the city, another an unfinished chess game, yet another matrix of some sort with various characters and sybols across numbers. It also seems that he was preparing a kind of a document with text written on it, some of which doesn't make a lot of sense. The text was:

The Roman says -

    If you knew what I got,        
    you'd have known the plot.
    Till the cops were brought,        
    the body got rot.        

    The sun had set,
    and it lay there unseen
    Till the time had come
    for the number Thirteen

'frnepu gur png, ova, try, she'

You take notes, and decide to look into it later.

You look at the chess game and observe that he had entered a weird name as his own (probably a code).

'mr tngu ab zhyr'

You then look at the map, and see that various locations are marked with text

k1 m9 t3 n6 a2 k15 p10 j7 t4 c2

At the bottom of the map

'shim ta bilt kora mietylo'

You take notes again.

You take a look at the body again, and see that the fur lining of his coat is torn apart at the corner. You bend and inspect and find a small piece of paper inside with a note saying,

'pqyqfnssaf'

Now you start to wonder if your friend's sanity had taken his leave. You can't help remembering odd things about your friend and start feeling unsettled. You shake your head and ... you suddenly hear purring from the corner of the room at see his old cat just sitting there as if nothing had happened. You go and pick the cat up and find a parchment piece poking out from its collar. You unfold it and see now familiarly odd text written on it.

'envyf tb mvtmnt'

You take note, and start looking around for more clues. You look at all the clothes on the bed and nothing...under the bed and nothing...inside the pillow covers and...find a note saying,

'prnrh ugth soygfrpn thjjwe'

Put it in the evidence bag and take notes. You move on to the next room, a poster there showing an alien saying "I'm from Area51"; you smile, and as you were just about to leave the room you notice something scribbled at the bottom of the poster. You go closer and take a look:

'K to m9' 'BB to p10' 'R to k1' 'Q to m9' 'sup sup'

They seem like chess moves but these blocks don't exist on the chess board. You go back to the computer and look at the chess game and shockingly you see that all the blocks are numbered weirdly. As if by instinct you look at the map and see the marked locations all have numbers on the chess board. Royally confused, you sit down to think. Just a few seconds into an argument with yourself your eyes wander to the trash bin and see a crumpled piece of paper inside. You un-crumple it to see similar text on it.

'ksadeplpzd'

Thoroughly confused, you take notes again and decide to move on to find more clues. You head into the bathroom; looking around, you pick up the shower gel and see a piece of plastic taped to it on one side with the text saying,

'ieassruoke'

You shake your head again in utter confusion. You decide you have had enough and after telling the cops to notify you of any development you go back to your house.

It's almost mid-night and after having a scotch you decide to hit the sack. You fall asleep right away. Just a few minutes of very light sleep and you wake up suddenly. No, it's not possible. You pick up your notes, smile and think. You go to the computer and and verify your findings. Assured, you smile again and think, "It's just like Toboggan, even at the last moment, so many misleading clues. Rest in Peace my friend. You solved it at last."

Who did it?

Note: It's a Cryptology puzzle. Some of the clues might be misleading, but if you solve it properly, you will not be misled.

Answer 1

The answer is:

Keyser Soze

Which is a reference to one of my favourite movies:

The Usual Suspects

The first step was to decrypt the text at the bottom of the note using

ROT-13, from Rot and Thirteen in the plain text. The reference to Caesar was helpful as well.

This yields:

search the cat, bin, gel, fur

Next find all of the clues in order. The cat clue: "envyf tb mvtmnt" decrypts to "rails go zigzag". The other three clues are bin: ksadeplpzd, gel: ieassruoke, and fur: pqyqfnssaf. Every other clue in this puzzle is a red herring.

I was initially tripped up at this point because I was trying to use an actual Rail Fence cipher. However the three clues listed like so:

ksadeplpzd
ieassruoke
pqyqfnssaf

Travel down the diagonal from top left to bottom and then mirror the angle and head back to the top. Repeat until the end is reached:

Answer 2

PARTIAL ANSWER

The first sequence

frnepu gur png, ova, try, she

can be decrypted using a simple ROT13 as follows:

search the cat, bin, gel, fur

The hint was contained in the first line, where the "Roman" clearly alludes to Caesar (cipher).

The cat, the bin, the shampoo and the fur indeed have their own encrypted messages, but I haven't decrypted them yet. On the contrary, the roof isn't mentioned in the problem.

If I make progress, I'll add them to this answer!