Former death row inmate Damien Echols, whose story is the subject of the new documentary “West of Memphis,” was at Brandeis Tuesday to speak at the Schuster Institute for Investigative Journalism. Echols, who lives in Salem now with his wife, Lorri Davis, spent more than 18 years on death row after being convicted of killing three young boys in Arkansas. He and codefendants Jason Baldwin and Jessie Misskelley Jr. — known collectively as the “West Memphis Three” — were released from prison last summer. (Echols was joined at Brandeis by Erin Moriarty of the CBS News show “48 Hours” and Lonnie Soury, who advised the legal team that defended and eventually sprung Echols and the others.) The West Memphis Three case has attracted considerable attention from celebrities, including Johnny Depp, Eddie Vedder, director Peter Jackson, Marilyn Manson, and Dixie Chick Natalie Maines.