Investigation questions for shady investigator?

[Davval]

So I am doing a campain where the second in command of an undercover organisation is kidnapped. This organisation is known to know pretty much everything going on in the region. Thats why a thieves guild would want to kidnap someone like him. I also thought that everything would be better for the thieves guild if they also had an insider, a tiefling that would be promoted to second in command if the other disappeared. And since the PCs are sort of witnesses to the crime someone would have to interrogate them, none other than the tiefling. So my question is what sort of questions would the tiefling NPC ask the PCs to make it sound like the truth but also drop some hints that he acctually was in on it the whole time.

[zminseo]

Here's what I would do:
Have the investigator ask a regular question(what did you see, where were you, etc.)
Have each PC roll an insight(WIS) check.
According to their results, tell them about what their character can feel about the investigator(for example, you feel like the tiefling is hiding something, and is acting cautious.)
Hope this helps:)

[Davval]

Here's what I would do:
Have the investigator ask a regular question(what did you see, where were you, etc.)
Have each PC roll an insight(WIS) check.
According to their results, tell them about what their character can feel about the investigator(for example, you feel like the tiefling is hiding something, and is acting cautious.)
Hope this helps:)

This is good but I thought maybe I could also drop some hints without using dice. Then they would really have to think about what he said to use it when further inspecting. Lets say for example the 2nd in command was drugged, maybe one of the PCs sees that but cannot react in time. And then the Tiefling askes "Did you get a look at the one who drugged him?" when in reality he wouldn't have known that he was drugged

[Unoriginal]

If the investigator is intentionally revealing he's in on it, I think he should rather make some seemingly off-hand comments that the PCs could catch on, like "oh yeah, this part of the city is so unsafe, especially if you're a thieves' guild's target" or pointing out a detail.

If the inverstigator is supposed to unwittingly reveal he's in on it... well, I got to ask: why? You don't get to be an infiltrator for the thieves' guild OR a potential second-in-command by having loose lips and self-sabotaging your chances.

It would be better if it was someone else that said something that tipped the PCs off, like a guard saying "you're lucky, [shady investigator] is usually way harsher with witnesses. You must have gotten on his good side", after the investigator asked them questions that are seemingly useful but don't actually let people find the kidnapping victime.

[Daithi]

You could also have the tiefling give the characters a good "questioning" (i.e. beating), and as one of them regains conscientiousness they overhear the tiefling say something to an underling that reveals his link to the crime or otherwise incriminates him.

Maybe even have the tiefling try to frame them for the crime. Even if he just threatens to do so, your characters may start to see him as a suspect.