The aide asked whether the security team should receive his official photograph.
The deputy chief refused.
She instructed the aide to leave access arrangements to her office.
The investigators interviewed the aide.
She explained that she'd been surprised by the instruction.
In previous leadership transitions, security personnel received clear information about incoming officials.
This time, the deputy chief had insisted the matter was being handled privately.
The aide had complied.
She didn't know the purpose of the arrangement.
But she remembered the conversation.
Her account was supported by the preserved communication record.
Another employee confirmed that the deputy chief asked about the status of the exterior camera system shortly before the commissioner arrived.
The available technical evidence showed that the recording configuration was altered through credentials associated with her office.
The investigation couldn't establish from that fact alone that she personally operated the system.
But combined with additional records, the evidence became increasingly significant.
Then investigators found a second video source.
It wasn't part of the headquarters security network.
A municipal traffic-monitoring camera across the street had captured a wider view of the plaza.
Its angle wasn't ideal.
The sound was unavailable.
But the footage showed the sergeant stopping the commissioner, taking his identification, pushing him, and making the movement associated with the slap.
The video also showed the headquarters doors opening and the command staff rushing outside.
The investigators compared its timing with the young woman's recording.
The two sources supported one another.
The attempted interruption of the headquarters archive had not erased the event.
And the independent footage helped establish the sequence of actions without relying entirely on testimony from either man.
The deputy chief's attorney challenged certain interpretations of the evidence.
That was his responsibility.
He argued that the assignment had a legitimate security purpose and that the camera maintenance might have been unrelated.
The investigative team considered those explanations.
But the communications concerning the towing audit revealed another issue.
Before the commissioner's arrival, the deputy chief had discussed the possibility of delaying his review with an executive from the towing contractor.
The messages described the incoming commissioner as a threat to the existing arrangements.
They discussed buying time.
And they referred to creating a leadership transition problem.
When investigators compared those messages with the unusual security orders, the pattern became difficult to dismiss as coincidence.
The findings were submitted to the appropriate prosecutorial authorities.