My group are still playing the first adventure and managed to capture Filge alive (he surrendered when he realised he would be defeated) then after interogating him a while, they decided to kill him. Most are neutral and/or chaotic aligned, but none are evil.
It seems to me that though he is thoroughly unpleasant, there is no proof that Filge has killed anyone, and as he pointed out to the pcs, they did break into his property...
(I must admit the pcs had some provocation: the party thief had decided to solo the observatory and was killed by the Tomb mote when he broke into the store. Filge had 'invited' him to be a 'guest' at the dining-table by the time the rest of the party got there! Still as Filge pointed out he was a thief and had been killed by a 'guard-dog', not murdered.)
I'd be interested whether other DMs consider this an evil act, with possible alignment consequences etc., and if so how would they 'play' it.