YOU SAID:
I have killed my hamster
INTO JAPANESE
ハムスターを殺してしまいました
BACK INTO ENGLISH
i killed my hamster
INTO JAPANESE
ハムスターを殺した
BACK INTO ENGLISH
killed a hamster
INTO JAPANESE
ハムスターを殺した
BACK INTO ENGLISH
killed a hamster
That didn't even make that much sense in English.