the women killed his former lover and made it look like accident .The photographer was also in love with the former lover, so when he found out the truth the the girl killed him(former lover) ,he killed the girl and made it look like sucide.And as for the two girl the red hair girl is just a jealous bitch who love to see people get dumbed .but I believe the same way in the middle she started to like the blond girl or maybe just wanted to repay for sin so she helped her at the end
for the two girl i think the red head liked her since the beginning! she played with her with the help of the guy! like that the blond girl will trust only her! now she has her in the plam of her hand! after, she like her but in her weird way! That's what i understand here!
...but there are so much things I didn't understand how did the former lover died? Because I thought it was an accident but then that woman said that she had killed him (and then the photographer killed her...) and I don't understand the relationship between the two girls?? That was so sick, the redhead was so cruel with the blonde one...