First, Melissa and Ian did not kill Ali. If you want to know who killed Ali, and who A is, please read the long answer below! :)
*********&&&SERIOUS SPOLIER DO NOT READ IF YOU DON'T WANT TO KNOW WHO "A" IS&&&*********
A is Alison. Alison has a twin sister named Courtney who had mental problems and went to a hospital for that. One day when Courtney arrived home for a few hours, she started to act as Ali, and when Ali tried to tell her mom that she was the real Ali, her mom just thought she was Courtney and lying and she brought her to the mental hospital.
So, the day that Aria, Spencer, Emily, Hanna, and "Alison" had the sleepover, Courtney had gone Into the Woods and Ali killed her. She murdered her because she took her life away from her.
If you read the books, when Ali was living as Ali, she was friends with completely different people and still popular, pretty Ali. I think they mentioned it in the show, but the girls always wondered why she suddenly dropped Naomi and Riley (her friends before) and went to them. It is all explained in Wanted. :D
Read more: Who_is_A_in_pretty_litte_liars_book_series
No
a lot of people think ian was with ali at the Hilton head. he was actually with Melissa, getting an abortion because she was pregnant. he was just a very nice person and he didnt kill ali and he isn't A. that is why Melissa really wants her second baby. the bad thing is tho, ian had an affair wtih Spencer.
NO! Alison killed Courtney in the books. Melissa and Ian did not.
no , ali killed courtney who was pretending to be ali
Ian , who is now married to Spencer's sister- Melissa
No, -A killed Mellisa and Ian
Since it seems that you know that Ali had a twin, Ian DID NOT kill Courtney. The real Ali killed Ian maybe on suspicion that Ian had found out the truth about what happend the night "Ali" disappeared.
ali pushed ian off the bell tower, and he got strangled by the ropes poor guy
no
the real ali kills him for knowing about her twin courtney dilaurentis tricking evreyone into belive she was the real ali the real alison gets angry at the girls and ian for unknowingly ruining her life she also attempts to kill the liars twice once in the forest fire and once in the burning house. she kills ian and kidnapps melissa
Ali killed Ali. It's hard to explain. Read Wanted.
Ian is Melissa's high school boyfriend, who Alison was seeing behind her back. Ezra is arias bf. "Ali's killer is the REAL Alison. Courtney was the one who died that night. The actor that plays Ezra is Ian Harding, the person above probably got them mixed up.