In February it was revealed that Lucy's brother Bobby killed her on Good Friday last year – but parents Ian and Jane decided to cover for their young son.
The police are determined to find her killer and Ian and Jane are left shocked this month when somebody is arrested.
A source told the Mirror Online: "The arrest is going to be huge and send shockwaves through the Square.
"No one can quite believe it when it happens and it's going to tear families apart. Residents really have to decide where their loyalties are."
Ian, Jane, Cindy and Peter are the only ones who know Bobby killed Lucy – could one of them have slipped up and revealed the truth?
Most of the residents in Walford were in the frame for the young girl's murder at some point, so there is a good chance somebody completely innocent will be arrested for the crime.
Knowing the truth, it will undoubtedly be tough for Ian and Jane to watch on of their friends blamed for the horrific crime while they protect their son.
Who do you think the police will arrest for Lucy's murder?