Sorry for my poor English. I live in non English-speaking country.
It seems that all items in the merchant's stock disappear when I kill him/her, so I can only obtain what's in his/her pocket.
Of course, if I buy all items from the merchant before the slaughter, I can get not only all items but also the caps I used to buy those stuffs. However, I can't buy all items because they are too expensive.
(For example, Gloria Van Graff sells lots of things from GRA, and GRA's stuffs costs me a fortune.)
Is there a way to get all items of merchant before I kill him/her not using console commands?