Dixie Chicks star Natalie Maines included a cover of Dan Wilson's Free Life on her new solo album as a tribute to former incarcerated West Memphis Three member Damien Echols and his wife Lorri.

The singer was one of the leading celebrity campaigners fighting for the release of the three Arkansas men imprisoned for the murders of three boy scouts in 1993.

Echols, who was sentenced to death in 1994, and friends Jessie Misskelley, Jr. and Jason Baldwin were released in 2011 after serving 18 years behind bars for a crime most people - including Maines and Pearl Jam star Eddie Vedder - believe they did not commit.

The singer admits Wilson's anthem has meant a lot to her ever since the day her friend Echols won his freedom.

She tells The Hollywood Reporter, "That song is about the West Memphis Three. The words, to me, speak to their first year of freedom. I sang that song at a rally for them in Arkansas when they were still in prison, and Damien Echols' wife Lorri said she listened to the board tape of that song every day until his release. So I put that song on there for her and for them, and to speak to that time of my life.

"The day they got released was the greatest day of my life. I hate to say even more than the birth of my children. Don't tell them that! But it's something else to witness people get their lives back after 18 years of false imprisonment."

The West Memphis Three didn't win their freedom outright with pardons - Echols, Miskelley, Jr. and Baldwin had to enter Alford pleas, which allowed them to assert their innocence while acknowledging that prosecutors have enough evidence to convict them, before they were released. They were freed with 10-year suspended sentences.