CHICAGO (CBS) -- Seeking to set a tone for his leadership of the Chicago Police Department, interim Supt. Eddie Johnson told the latest class of police recruits Friday the public wants officers they can trust.

Johnson, a 27-year veteran of the department, attended his first department graduation as the head of the force on Friday, less than two weeks after Mayor Rahm Emanuel tapped him as the next superintendent.

At a Navy Pier graduation ceremony, the superintendent told a group of 74 police recruits, 32 new field training officers, and 38 newly promoted officers he never thought he'd be standing before them as the city's top cop, much less at a time when the department faces so many challenges, from the fallout of the Laquan McDonald shooting scandal and other high-profile allegations of police misconduct to a precipitous rise in shootings and murders to start 2016.

"I never thought that the mistakes or the poor judgment of a few could do so much to undermine the reputation and the integrity of so many good officers who put their lives on the line each and every day," he said.

Johnson told the recruits this is a time of challenges and unprecedented scrutiny for the department.

"Our relationship with the community that we serve is sacred. It's hard to earn trust, and it's easy to lose it," he said.

Once that trust is lost, Johnson said it's harder to earn back, but it can be done, and the way to do it is "with courage, determination, and honesty."

Johnson told the officers the public wants respect and officers they can trust.

"At the end of the day, your integrity, your character, and your reputation is all you have; and you need to protect it. You need to own it. You need to build it," he said.

In the wake of skyrocketing numbers of murders and shootings in Chicago, Johnson said there are about 1,000 individuals responsible for most of the violent crime in the city.

Through the end of March, murders were up 72 percent compared to 2015, and shootings were up 89 percent. So far, the city is on pace for about 560 homicides this year, with the warmest – and typically most violent – months of the year yet to come.

"I have a clear message to those individuals who are wreaking so much havoc on some of Chicago's communities: we know who you are, we know where you live, consider yourselves put on notice," Johnson said.

Although Johnson must still go through the formal application process and City Council confirmation before his appointment as superintendent is permanent, those steps appear to be a formality.

Emanuel rejected the three finalists sent to him by the Chicago Police Board last month, and said he will call for a new search. Johnson will apply and presumably will be one of the three finalistIn s this time around. The heads of the Black and Latino caucuses have both publicly backed Johnson's selection.