Hi Tolkemec
Im guessing you are using OHII
If so here is the defside for Sweden (by Gap

)
[SideEntry 188] ; ///////////////////////////////// S W E D E N \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ (Merchants, Warships, Ports, Airports, etc.)
Country=Sweden
Side=0
StartDate=19380101
EndDate=19451231
[SideEntry 189] ; ////////////////// S W E D I S H M E R C H A N T F L E E T \\\\\\\\\\\\\\\\\\\ (Merchants)
Country=FreeSweden
Side=1
StartDate=19390924 ; The Swedish steam merchant 'Gertrud Bratt' is stopped and sunk by U-4; she was carrying contraband. Althought Sweden was officially neutral for the whole duration of the conflict, its merchant vessels were a common presence in Allied convoys. From the outbreak of WWII until the defeat of Nazi Germany, 89 Swedish ships were sunk/damaged by German U-boat while they were sailing on their own or in Allied convoys.
EndDate=19450509 ; German Instrument of Surrender: German capitulation
As you can see it is set to neutral for the whole war - so not sure why you got a kill for that unless it was a freesweden ship.

Was the ship icon coloured green for neutral