A Boston dean and pastor has been accused of shooting a student execution style after the 17-year-old boy had been working to sell drugs for the man.

But that's not even the strangest part. Rev. Shaun O. Harrison Sr., who regularly spoke out against gang violence, guns, and drugs, was found to be leading a double life with a gang-related marijuana-selling operation on the side and several illegal guns found in his Boston home.

The 55-year-old pastor and father of eight also organized gun buy-back programs and spoke out regularly against violence, but his secret life was exposed by the English High School student when the execution failed.

Harrison was once the "unofficial" dean of students at Boston's English High School but has since been fired. He was also the pastor at the Charles Street African Methodist Episcopal Church, but officials there confirm that he left in 2012 to form his own non-denominational church.

When police arrived at Harrison's home to investigate after the shooting, they confronted three other suspects who were thought to be removing evidence from Harrison's home. Dante Lara, 24, Wilson Peguero, 23, and Oscar Pena, 19 were found in possession of marijuana, guns, and a police scanner when they were arrested by police. Officials also report that two of the men had tattoos similar to Harrison's, and a mural depicting the Latin Kings insignia was found on a wall inside Harrison's home. The police haven't connected the gang with Harrison, but the investigation is still underway.

During the initial hearing, Harrison, dressed in a gray suit and standing with his lawyer, shook his ghead while the allegations were being read. He denies all charges, despite the fact that a traffic camera caught the attempted execution on video and the 17-year-old student's testimony matches up with what was found in Harrison's home.

Harrison's sister, Susan, says that the whole thing was a set-up. "My brother is a good man, and I don't know how this happened," she said.

Harrison founded Operation Project Gang Out, an anti-violence initiative that asked young gang members to turn their guns into him with no questions asked. He also worked for Citizens for Safety and Operation Homefront, a clergy-run anti-violence group that has since removed Harrison's involvement from their Facebook page.

Harrison also ran for City Council in 2009, and mostly everyone who worked with him over the years says that he was a good man and these allegations are surprising.

"This is totally unexpected,"said Nancy Robinson, who worked with Harrison at Citizens for Safety. "I've never seen him lose his temper. Everything we do, and we work on, is to prevent this kind of incident."

But one high-ranking state official, who asked to remain anonymous, said that Harrison was not a "heavy hitter" for his efforts to rehabilitate young gang members. "We wouldn't summarily dismiss him, but he wasn't someone you would give a lot of credence to in terms of what he was saying.''

Harrison is currently being held on a $250,000 bail.