I'll try to put any details in spoilers.

I have to talk to Regis to but I'm unable to present him with the evidence he wants. I found Karl's diary, and . I did not show the diary to Papa.

Now I do not see options to show the diary to either Regis OR Papa, and now that I've spoken to and convinced the other people required for the quest, I do not see a quest marker telling me to see Regis even though he's the last one I need to convince.

Soooo I'm kind of stuck, and it's a bit annoying.

Bump.

I'm having the same problem only i never killed Karl because i never got an option to taunt him.
Seriously this game is becoming a let down because of all these bugs and glitches in the game.

Same here. I have the "Karl's Journal" note on my Pip-Boy, but it doesnt trigger a dialogue option with either Papa Khan or Regis.

OK well I loaded a much earlier save and the only way I was able to do the quest was to convince all the people up until Regis, THEN go find Karl's diary and take the diary to Papa Khan. If I try to pass that speech check to make Karl show his true feelings I'm unable to complete the quest, because then I don't get the option to show the diary to Papa Khan or Regis.

So it seems like poking around and getting the diary early could actually be really bad for the quest, and the speech method of dealing with Karl ends with a dead end too.

Ok are there anyway to bypass that stage of the quest? With console maybe?

bump