aggressive bengal

i really hope someone can help me,to startwith we have 3 cats 2 bengals milly 2yrs 7 mths and billy 2 in december and winston 6 mths.
there was the usual upset in the begining,growling hissing etc.. when wiston was introduced to them but after 3 weeks everything settled down,they were all grooming each other sleeping together etc..
however 3 weeks ago a neighbour told us billy had attacked 2 cats in the area causing large vet bills. it was hard to believe it was our billy they were talking about as he,s such a softy.
then a week ago he attacked milly.
milly and winston now give him a wide berth to avoid confrontation but the growling and snarling is begining to scare me.
billy will however share his food bowl with the other cats making no noise its only when he,s walking about and comes accross them it starts.
i hope someone out there will be able to advise us.
many thanks
kerry

My first thought is....is he neutered? If not, it is a fair bet that he needs to be. Whole males can be very aggressive. There really is no way to retrain an aggressive cat outside of prozac. If it continues and he is neutered, I would think about keeping him inside and away from cats outside his home circle.

thank you for your reply
billy is neutered he was done at 4 months,milly has been spayed and winston neutered last week.
i have never heard of cats being given prozac.
i cannot say i like the idea even if the vet agreeed,however keeping him whilst the others go out seems cruel as well.
i think i had better make an appointment with our vet to disscuss it further.
we did mention the fighting with other cats last week at the vets and was told thats what cats do which was not very helpful but in every other way our vet has been great.
it is all such a worry thank you very much for your reply though.
kerry