Her only known family are the Mathesons and she attended the Ravenswood City Celebration with her cousin Luke. Implying that she too is a resident of Ravenswood however It's unlikely she was still living in Ravenswood due to not being mention by her cousins or being seen in the short lived titular series.
Leah is at the Celebration talking to a guy in low voices, but she quickly leaves him. Alone, Aria Montgomery follows Leah and helps her out of an empty grave, which she had fallen into. Aria asks if she was pushed by the guy she was with earlier, but Leah says that is her cousin and that he wasn't behind this. Luke arrives, tells her that the graveyard isn't safe and they leave.
She has long blonde hair styled curly and somewhat wavy with blue eyes.
Elizabeth Whitson appears in this episode as a character named Leah, who is appearantly Luke's cousin. However, when this episode was shot Whitson was still going to play Olivia, Luke's twin sister, in the actual spin-off show. The role was recast with Merrit Patterson after this episode was shot and before the first episode for Ravenswood was shot. If you look closely you can see the dialogue was changed during post-production and doesn't match up with what her lips are saying. Her lips are saying 'No, that was my brother', but we're hearing 'cousin' instead of 'brother'. When Luke calls her 'Leah', that's also off-screen. He was probably calling her 'Olivia' before.