Prayer vigils are being held in churches in Boston and around the nation for the nine shooting victims that were killed at one of the South’s most historic black churches, Emanuel African Methodist Episcopal Church on Calhoun Street in Charleston, South Carolina.

Jack Levin, who Co-directs the Brudnick Center on Violence and Conflict at Northeastern University and is the Author of more than 30 books on hate crimes and mass murders, says this was a very rare hate crime. He says, “the typical hate attack is committed, mostly be teenagers or a group of older youths or friends who go out on a Saturday night looking for someone to bash and assault; they don’t’ commit murder, they may vandalize or hurt someone, and they do it because it gives them a thrill.”

As the country examines the tragedy that unfolded Thursday, many are reflecting on the lives that were lost, and expressing outrage and asking the obvious question surrounding a motive for the mass killing: What would prompt accused suspect, 21-year old Dylann Storm Roof, to carry out such a crime, especially while people were worshipping in church?

Roof, who reportedly had an unsettled personal life and a recent history of documented anti-black views, committed a mass murder, which Levin says, “ rarely happens, maybe once year, which is documented over the last few decades.”

Levin, who studies and researches hate crimes and mass murders at JackLevinOnViolence.com, says Roof,  was different than most hate crimes suspects.  Levin says Roof committed mass murder , "and led a life of frustration in school, at home, he was a loner, and he externalized responsibility and placed blame, especially on black Americans for everything wrong in his life. He convinced himself that black Americans were the enemy and went to the church to quote- “rid the world of evil, “according to Levin.

Levin says, he thinks prior to the killings when Roof sat in on the prayer service, "he was enjoying himself knowing he was going to take out so many lives," and Levin says, " that was mostly likely pleasurable to him.”

To listen to Jack Levin's entire interview with WGBH Morning Edition host Bob Seay, click on the audio file above.