Officers executed a search warrant Friday at the Rev. Shaun O. Harrison Sr.’s residence on Pompeii Street, where they discovered two handguns, a rifle, a shotgun, different calibers of ammunition, enough cocaine to merit trafficking charges, and a large amount of marijuana, Boston police said.

A minister and former English High School dean accused in an “execution-style” shooting of a 17-year-old student is expected to face additional charges after investigators found guns, ammunition, cocaine, and marijuana in his Roxbury home, officials said Saturday.

Items Boston Police said they seized in the apartment of the Rev. Shaun O. Harrison Sr.

Investigators saw a large gang mural inside Harrison’s residence, police said.

Harrison, 55, is being held on $250,000 bail on charges that he shot an English High student in the back of the head Tuesday evening on Magazine Street in Roxbury. He pleaded not guilty Thursday in the Roxbury division of the Boston Municipal Court.


Officials have not determined what additional charges Harrison may face as a result of the seizures, said Jake Wark, spokesman for Suffolk District Attorney Daniel F. Conley.

“With the benefit of high bail, we have time to proceed methodically and bring the best and strongest case,” Wark said.

Harrison’s lawyer, Kernahan Buck, did not return messages Saturday.

The drug and gun seizures came after police arrested three men Wednesday who are believed to have removed evidence from Harrison’s apartment.

Police charged Oscar Pena, 19; Wilson Peguero, 23; and Dante Lara, 24, with drug offenses. Lara and Pena also face firearms charges.

Officers who searched Lara and Pena found a 9mm semiautomatic firearm, .45 caliber semiautomatic firearm, ammunition, and substances suspected to be marijuana and cocaine, according to a police report filed in the Roxbury division of the Boston Municipal Court.

All three pleaded not guilty.

Prosecutors say Harrison shot the teen after a dispute. The teen told police he had been enlisted by the minister to sell marijuana and had been doing so for several months, Suffolk Assistant District Attorney David Bradley said in court Thursday.


When they met Tuesday evening, Harrison told the teen they were headed to a house to get marijuana and meet girls, Bradley said.

Surveillance video that prosecutors allege captured the shooting shows a man on a cellphone raise his hand toward the head of a person walking in front of him. The man on the phone then flees.

The boy survived, despite being shot behind the ear, officials said.

The student identified Harrison, and told investigators the man he considered a mentor and called “Rev” kept a rifle and shotgun in his apartment, where he also displayed a mural depicting Latin Kings gang members, Bradley said.

The allegations against Harrison stand in stark contrast to the reputation he developed as antigang activist who participated in gun buyback efforts with Boston police.

He joined the Boston Public Schools in 2010, becoming “dean of academy” at English High School on Jan. 5 after holding jobs at the now-closed Odyssey High School in South Boston, Boston Green Academy, and Orchard Gardens K-8 Pilot School, said Denise Snyder, a school spokeswoman.

None of the positions required education licenses or certifications, she said. Harrison was fired Thursday after officials learned of his arrest.

He was also known as being a member of the Gun Owner’s Action League and told Cam Edwards of NRA News in 2011 that he supported educating children about firearms in schools and community centers, according to an interview posted to YouTube.


In 2012, Harrison established Clergy Home Visits Inc., which described itself as a service for at-risk school students, according to records filed with Secretary of State William F. Galvin.

The Rev. Christo Kamara, senior pastor at St. Paul’s Victory Christian Assembly of God in Mattapan, said on Saturday that Harrison coordinated visits that clergy and Boston school police made to students in need and their parents.

He said Harrison had a good relationship with police. “For me to hear something like this is very, very surprising,” Kamara said.

Harrison has been associated with different Boston churches over the years, including Charles Street A.M.E. Church and Mt. Calvary Baptist Church, though he no longer attends at either location, according to their pastors.

For six months last year, Harrison attended at Hampton Outreach Ministry, which is now called Refuge Deliverance Outreach Church, said George Hampton, the pastor.

Harrison acted as a “worship leader” charged with coordinating and hosting services and making announcements, Hampton said. He said Harrison stopped attending services in September when the church moved to a new location in Dorchester. Hampton believed Harrison wanted to devote more time to combatting gang violence.

“We are out of our minds,” Hampton said. “Everybody is saying, you know, that [this is what] he preached against and fought against. How in the world could he be one of the perpetrators? ”

The Rev. Shaun O. Harrison Sr. was arraigned in Roxbury Municipal Court Thursday. Aram Boghosian for The Boston Globe

Laura Crimaldi can be reached at laura.crimaldi@globe.com.