Pretty empty... except for WO and spears all around looking for hidden enemies... I'd say it's not the best day to carry the body of a grown man in garrish clothes surreptiously out of the palace, and then what? Out the front gate and into the Queen's plaza?

Even if we dismiss those substantial difficulties (increased if the killer isn't a strong man or doesn't know the palace extremely well), the question remains: was there a non-channeller who could have killed Asmodean who had a strong enough motive to risk carrying the body out of the palace instead of simply leaving it there? It's not like Rand would call the C.S.I. team to analyze the wound or look for DNA.... Which non-channeller really had a motive to kill Asmodean but didn't want the body found? Not an Aiel for sure, even if they knew he was Forsaken, they would kill him and go to Rand to tell him "I could not let the man live knowing he was a shadowrunner Rand al'Thor, but now I have toh".

I can't really think of anyone (among the believable suspects anyway) with a motive to hide the body. Even Slayer would not really have a personal motive to do that and he really would have to be firmly ordered to leave no trace behind (and why?) because otherwise he always left his kills in plain view, the more gruesome the sights the better (animals in the TR, grey men, horrifically "staged" BA corpses in Tear, those folks in Far Madding). Slayer is a bloodthirsty butcher and a show-off, and that's part of his M.O. as a killer to overdo the butchery and leave evidence of his skills behind. He's not an "assassin type" good at all at stealth either, he's been glimpsed in Tar Valon and numerous time while he was spying in TAR, often by unskilled people at that). He even brought trophies of his kills to the folks of Emond's Field as Lord Luc - gave severed heads of shadowspawn to kids, much to Perrin's annoyance.

On the other hand, the Forsaken all had motives not to let any evidence of a murder behind: that way Rand wouldn't assume right away a Forsaken came to kill Asmodean right under his nose. If there was a body, someone would/might have tried to read residues etc. Rand could fetch Callandor at any time, they all knew this. Graendal and Sammael especially had all the reasons in the world to destroy Asmodean body if they came to scout and try to learn what happened, if Rand was allied with just Asmodean or had also Lanfear with him now, what were his plans ... and one of them bumped into Asmodean. Personally, I believe both of them came to Caemlyn to investigate, on that day or in the next days at the latest (just like Graendal also has done in Illian right after Sammael's demise, again right under Rand's nose). Both of them were in danger. They needed to know why Rand attacked Rahvin instead of being baited to Illian as planned. Did he find out about Rahvin on his own (and then why did he attack?) or did someone betrayed him? Would it stop there or would Rand then move to eliminate Graendal and Sammael one by one too? Asmodean knew where Graendal hid, Rand knew about Sammael. If Lanfear had brought Rand to her side and betrayed them all, Graendal and Sammael both needed to find that out, and urgently. Personally, I believe both of them have visited Caemlyn, and one of them bumped into Asmodean by accident and killed him.

Sammael got himself spies near Rand, it's obvious. Later on, he knew Asmodean and Lanfear were never seen near Rand, and he believed Lanfear has gone in hiding and Asmodean has been hidden somewhere by Rand. He thinks Lanfear betrayed them. In LOC, it appears Sammael's spies reported to him that Rand was meeting a man secretely at the Cairhien Academy, a place where scholars were inventing new weapons for him. Personally, I'm quite convinced the reason why Sammael sent his gholam to kill Herid Fel is that he thought he had found the alias under which Rand had hidden Asmodean, and that Asmodean was still teaching him/passing him important information about his foes etc. He needed to stop Asmodean from teaching Rand, especially that Sammael no doubt had heard that Rand was also setting up a training center for male channellers (Sammael probably had spies there too, btw. It's the first place he would have suspected Rand to hide Asmodean)... It was a complete overkill otherwise to use a gholam to kill a feeble old non-channelling scholar who often spent time alone fishing. The dumbest local one-handed DF with a badly sharphened rusty dagger could have easily killed Herid Fel... unless the one who sent the gholam believed Fel to be a very dangerous channeller. Jordan even left us a clue a gholam can be used to assassinate another Chosen: Graendal was surprised by a gholam once and nearly died.

Graendal also got herself spies near Rand (that got confirmed in TGS, though we don't know when it started). She's learned much about Rand around the time Asmodean died (even details about his attitude toward women, details about the Aiel etc), and she's got reports about Lanfear dying in Cairhien the same day Rahvin was attacked. Unlike Sammael, she is also convinced Asmodean is dead. If she has not killed him, either Shai'tan told her as he did Demandred (she paid a visit to SG, we know this), or she's learned from her spies that Rand too had no idea what happened to his "gleeman". If she didn't kill Asmodean, she probably thought Sammael did and when she spoke of her conviction that Asmodean was dead she was in fact fishing for a confirmation from Sammael.

We've actually seen in TGS a pantry (it's a room and not a closet like the modern definition of the word) like the one Asmodean thought might be somewhere behind that door he opened (it probably looked like a door for servants - smaller and more discreet than the other doors for the masters, that's why he would think there might find the pantry somewhere that way). When Nynaeve decided to learn the truth of what was going on in the Chadmar mansion, she went straight to the pantry to find servants on duty, waiting there for any call (that's what the purpose of a pantry is: a room where servants wait for calls. It often has basics goods the masters often ask for - like pipes/cigars, wine, tea, scotch and what's needed to serve them). There, she forced one of them to go fetch the woman in charge of the household for her. It's that woman she questionned, it's that woman who always know what there is to know in a house/palace. Ironically, Nyaneve's little visit to the pantry eventually lead to finding Graendal's palace. Jordan loved that sort of inversion/repetition with variations. I think that's pretty much what happened with Asmodean: Graendal came to Caemlyn to find out what happened to Rahvin. Lanfear and Moghedien had also vanished that day, this was getting quite alarming. She could not just wander around the palace, so she went to a servant pantry near the throne room Rahvin used (and that she no doubt visited at some point) and compelled one of them to fetch her the woman in charge of staff (Renee Harfor). She then compelled Renee to set the palace servants to spy on Rand and his people and report everything to her. Graendal would come occasionally to get her reports, in the meantime she would forget everything about this and obey subsconciously. At some point (while she waited for Renee or whatever, it really doesn't matter), Asmodean fatefully decided to seek the servants' pantry, opened the wrong door and saw Graendal with servants. And then he died... Graendal used the most minute amount of balefire, because she could not risk raising the alarm. In a way she must have known it was safe to channel, because WO were channelling all over the place. But if she removed more than seconds or at most a few minutes to Asmodean's thread, she ran the risk some balefire paradoxes would be noticed by people Asmodean was interacting with minutes ago, and for all she knew, Rand was nearby or knew where Asmodean was going... She saw she seemed safe and no alarm was raised, she finished her compulsion business and Travelled away.

She probably did somethign similar in Cairhien, and later in Illian. She got herself spies everywhere, we know this. She even has some near Mesaana (it sounds like her disguise is good enough to fool Aes Sedai, Aviarin included, but could be somewhat obvious to someone who knows her, her preferences and the way she likes to infiltrate organizations - she might have favourite positions she likes to hold - among those with access to younglings for instance, that helped Graendal to narrow it down. In the AOL, Mesaana created herself networks of very young infiltrators and killers. She could be a sister teaching a lot of novice classes).