The rolls from Crush and Aria make this a straight roll for him... I'll do this one out on the open just for fun.

4

The dwarf's eyes glaze over, and he begins speaking. "Well, I don't know who brought him in, usually either someone from the Guard or one of the body collectors bring strays like this in. Heard they found him hanging outside the city, all beat up like this. If he had anything on him it wouldn't be here, either the Guards have it if they're investigating him, which I doubt, or if a collector brought him in he has it, or they just left it all where they found him. I don't know."

"Is there someone who would know who brought him in?" Aria asks. "I'm sure you're busy and would love for us to be out of your hair."

The dwarf looks over his shoulder and shouts, "Hey, any of you know who brought in this Tiefling? The one that got strung up outside of the city?"

Another dwarf shouts back, "Ehhhh... Guards got him from the collectors, I think."

"You think? Or you know?"

"Ehhhh...I think they had him before we did, ain't we supposed to just dump him? No one's comin' to claim him anyway, been here long enough."

(I will have an update on Duncan tomorrow, provided life cooperates).

Perhaps, says Sen politely, hoping that the suggestion is still in effect, you could persuade your fellows to tell us exactly which guards were involved too.  He smiles encouragingly, or at least does his best to imitate an encouraging smile.

Outside, Usul is pleasantly surprised to see Duncan has returned. His owl familiar communicates to him that he followed the Ravens as far as he could, but that they split into two groups. One stayed atop an inn/tavern called Red's, the other group flew south by south east out of the city, but he didn't follow. He's not sure which group Frank went with.

Inside, the dwarf talking to the party says, "Hey, who's the guard what brought this one in? Was it Tobor? Or Johann? It was Tobor, right?"

"I don't know!"
"They all look alike Kiefl, you know that."
"Why're ya so interested in this Tieflin' anyway?"

"Just trying to help my new friends out," says Kiefl.

"New ... friends?" the dwarves stop their work and look at the party.  

Aria smiles awkwardly and waves to the other dwarves. "Friends!"

Friends, repeats Sen firmly.

Crush will grunt and shrug.

A group perception check from the dwarves, just for fun: 7

Aria and Sen say "friends" and the dwarves shrug. 
"If you say so."
"Look at Kiefl, makin' friends."

Aria nods. "Yes friends with Kiefl. We could all be friends. It's always a good idea to be friends with us." She awkwardly tries to flirt smile with the other dwarves, but she's not really good at that sort of thing. So it might come across as a confused smile. "It'd really be nice if our new friends could point us in the right direction of the collector who brought him in."

The dwarves laugh nervously, Kiefl especially. "Hey, we can point you maybe to the Guards who dealt with this, that's no problem. But those body collectors, we just, we just, listen... we just try to figure out what happened to them, we don't..."

Kiefl is genuinely nervous about this, like he's scared. They all seem scared.

"Those guys is cut from a different cloth."

"Cloth like scarecrow?" Crush would say with a grunt.

The dwarves laugh nervously. 
Kiefl says, "Scarecrow? No, it's just..those boys ain't right."

"Crush no afraid of children..." The orc would say shaking his head. "I talk... Crush good at talk" The orc would say with a grunt. "You tell where find no right boys."

Marvelling that once again it will be Crush who succeeds in getting the crucial information, Sen hangs back and hides a smile.

Kiefl says, "You guys actually want to find the body collectors? They're at--"

He stops, thinking hard, brow furrowed. 

"Those guys even have an office?" he asks the others.

The dwarves look at each other, like this is a question they've never actually thought about before, because who would ever want to go meet with the body collectors?

(sorry for not having more, super busy night. I'll add more tomorrow).

"Why wouldn't we want to find the body collectors? Is there something we're missing?" Aria interjects. "If they have information we need, then there's no other way to get it but to find them."

 With only a few short months in the city of Waterdeep, Sen tries to think if he's heard anything of 'body collectors' - do they have a reputation?  HIstory 20

"Tell Crush where bad kids!" The orc would repeat as he begins to get frustrated ..

Sen would know that the business of gathering and disposing of the, quite frankly, absurd amount of deceased people in and around Water Deep is a mysterious process. He knows that what the dwarves are doing--unceremoniously dumping bodies off the cliff into the sea below--is done because it's the most pragmatic way for this particular location to operate without having a massive number of corpses stacked on top of each other. As for the body collectors, Sen knows that this is a really mysterious group of people who's job it is to scour the city looking for the dead (who have not been reanimated in any form or fashion (yet)). There are all sorts of urban legends about them: that they are dead themselves, attempting to curry favor with the gods by collecting and turning in other dead bodies as a sort of metaphysical snitching, or maybe they're feeding on them somehow, or maybe they're demons the Masked Lords have signed a deal with, or maybe they're the Masked Lords themselves feasting on the souls of the deceased. As urban legends go, this one has run wild, and someone like Sen would probably not be thrilled at the idea of trying to make a direct approach to discover them.

Kiefl says, "Uhh, I don't know if they're kids, but I've heard they're bad, bad. Worse than just naughty children." then he looks at Crush and whispers "I heard they eat souls."

EDIT: Sen would know this is a possibility, but that it could also be a part of the urban legend. Aria and Crush passively would know this guy isn't trying to BS them.