CHICAGO (CBS) — The attorney for Chicago Police Officer Jason Van Dyke said his client is struggling with feelings of responsibility for his colleagues’ legal troubles, with the Police Department seeking to fire four other officers for allegedly lying about the shooting of Laquan McDonald.

Last month, Police Supt. Eddie Johnson asked the Chicago Police Board to fire Van Dyke and four other officers for lying about the circumstances of the October 2014 shooting that left Laquan McDonald dead.

Van Dyke has been charged with murder for shooting McDonald 16 times. Police originally said McDonald lunged at officers with a knife, but dashcam video released last year shows the teenager walking away from police when Van Dyke shot him.

Several other officers have retired or resigned before the department could move forward with efforts to fire them for allegedly trying to cover up the shooting.

“He was fine when it was just him that was looking at severe consequences, but when he sees fellow officers resigning and getting fired, it’s been extremely difficult for him,” Van Dyke’s defense attorney, Daniel Herbert, said at a Police Board hearing on Monday.

Johnson has accused Van Dyke, Sgt. Stephen Franko, Officer Janet Mondragon, Officer Daphne Sebastian, and Officer Ricardo Viramontes of violating departmental rules prohibiting filing false reports.

“He feels responsible, and he shouldn’t, but the fact is it’s very difficult for him,” Herbert said.

On Monday, the officers’ attorneys filed motions asking the city to lay out specific allegations against them.

“We’re going to ask the superintendent to specify the charges in a much more streamlined manner, so that we have an opportunity to defend ourselves, because the way it’s worded right now, it’s almost impossible to determine what the superintendent is alleging is the misconduct,” Herbert said.

The officers’ attorneys also opposed a request by the city to consolidate their cases, arguing there is a big difference in the allegations against each individual officer.

Franko’s attorney said his client was not even at the scene when McDonald was shot.