Lineolated Parakeets

Question
I had two Lineolated Parakeet hens and they lived together for almost two years in the same cage. First I had "Peanut" and I got her a companion "Cactus", (long story short) they bonded and would sit together and groom each other and all seemed well until yesterday. First I need to backtrack a little, they would fight occasionally, beaking each other but it ususally didn't amount to anything and minutes later they would be sitting together again. My heart broke when I found Peanut's body at the bottom of the cage dead and quite mutilated in the morning. Her left wing appeared to be chewed off almost to the shoulder, her right wing looked as if it had been nibbled on the edges.  Her head was partially bald and there were feathers everywhere, smears of blood on the food dishes and on the sides of the bottom of the cage.  I was beside myself with shock and deep sadness that Cactus could do such a thing.  My question is (since I wasn't home when this occured) as to what in the world went wrong with these two and why now? I would really appreciate it very much if you had any ideas as to what could have contributed to such violent behaviour.

Answer
Hello Jaimie and thank you for your post.
I am so sorry for your loss.  It's always heartbreaking when we lose one of our little friends, especially in such a violent way.  
If they were both females, then they could have reached maturity enough that they were fighting over territory, which they will do.
If you are going to get get replacement for Peanut, I suggest that you keep the two separated as Cactus will more than likely kill another bird that is put in with her.  Even if it is a male.  

Again, I am sorry for your loss.

Good luck and God Bless.
Dianna