Malcolm Turner Webb was 22 when he was shot and killed in Baltimore on December 15, 2016, about a month before he was due to testify in an attempted murder case related to a 2015 shooting he had survived. After the earlier shooting Webb identified an assailant from his hospital bed and cooperated with prosecutors, but testified before a grand jury only to begin receiving threatening messages on his Instagram account aimed at him and his friends to prevent his testimony.

His murder halted the prosecution of the man accused in the 2015 attack, Wayne Johnson Jr., and detectives later named a suspect in Webb’s killing who was serving time for another murder. Investigators say an anonymous tipster called in information but was too afraid to testify. The case remains officially unsolved.

If anyone knew Malcolm, witnessed the December 15 shooting, or has information that could be shared safely, please come forward.