The city's acting school chief said an incident in which the Rev. Shaun Harrison was alleged to have made sexual remarks to students at the Green Academy four years ago led to discipline but was not grounds for firing, while Boston's top cop says complaints of drug activity on his street led to surveillance last year -- but never turned up any actionable evidence.

Interim schools Superintendent John McDonough spoke to the press as he came out of a meeting with Mayor Martin J. Walshtoday on the arrest of Harrison in the attempted murder of a student prosecutors say he had put to work selling drugs.

McDonough offered no details on the complaint at Green Academy,  but he said, "The incident at Green Academy, that was dealt with appropriately. It was recorded and it was documented and there was disciplinary action taken at the time, but that incident in and of itself was not grounds for termination."

McDonough added that if "there are a number of behaviors and a progression of incidents that would indicate warranting more aggressive action be taken, it simply was not indicated in this case."

Walsh met with school and police leaders this afternoon after launching an internal inquiry into Harrison's employment history in the schools, where he seerved variously as a teacher's aide and a parent-student coordinator, most recently with the title of "dean of academy" at Boston English High School.

Police Commissioner William Evans, coming out of the same meeting, said a police drug unit sat on Harrison's street, outside his house, on two occasions in late spring and early summer of last year in response to complaints to CrimeStoppers and to the drug unit about possible drug dealing out of Harrison's three-unit dwelling.

"Our officers sat outside that location for weeks on weeks and we saw nothing to indicate the coming and going," Evans said. "There was people coming and going, but they were staying quite a long time, so those aren't indicators of active drug dealing going on. But we vetted those out. The two complaints we did get, we acted on. But we didn't see anything to take it to the next level ... There was nothing to indicate that this fellow needed to be watched any closer."

Walsh said in a statement earlier yesterday, “The charges against Shaun Harrison are extremely disturbing and I am greatly concerned because of his role with students at English High School. It’s critical that, in addition to a criminal investigation, we take a thorough look at his employment within our public school system to ensure that we are taking the necessary steps to protect students throughout the city.”

The city inquiry will involve interviews with school leaders and staff at schools where Harrison was employed, Walsh’s office said.

“An initial review of Mr. Harrison’s official records with Boston Public Schools shows no evidence that would have linked him to criminal activity in or out of school,” according to the mayor’s office.

IMcDonough said in a statement today that his “top concern remains the well-being of the students at English High School.”

“I have directed additional staff be assigned to the school to help support students and staff through this difficult time,” McDonough said. “I spent time at the school on Friday, and I have great confidence in the educators and staff at the school. We have begun a methodical process that will take a comprehensive look at Mr. Harrison’s employment history with BPS. When it is concluded, we will share as much of what we learn as is allowed by state law.”