Jason Baldwin, Jessie Misskelley Jr. and Damien Echols were tried and convicted of the murders as teenagers in 1994 and together they served 18 years in prison for the crime. The trio was set free in August (11) after admitting guilt.
Now Pirates of the Caribbean star Depp is encouraging officials to continue their legal investigation into the killings.
During an interview with Larry King on CNN Presents, he says, ""Admitting guilt (while) maintaining innocence, it's a really floppy piece of ground to stand on. I knew immediately when I first started to familiarise myself with the case, I knew instantly that they were innocent, that they were wrongfully accused. The more research I did, the more people I spoke to, it was absolutely apparent...
""It was ugly and a raw deal from the get-go back in '93... When you're thinking of these three kids, one, Damien Echols, on death row for 18 years, spent 10 years in isolation, for a crime that he did not commit.""
And the actor is secretly holding out hope U.S. President Barack Obama will pardon the controversial West Memphis Three and clear each of their records.
He adds, ""I mean, it would be wonderful if he did, but I think he's got a few other things on his mind at the moment... What I'm hoping is that the investigation will continue outside of the courthouse right now and that we will be able to prove the real killers.""
Depp isn't the only celebrity fighting for justice for the West Memphis Three - rocker Eddie Vedder and Dixie Chicks star Natalie Maines have been close to the case for years and moviemaker Peter Jackson has been quietly funding a private investigation into the murders.