NEW ORLEANS — Justice Department officials on Thursday released the findings of a 10-month investigation into this city’s Police Department, revealing a force that is profoundly and alarmingly troubled and setting in motion a process for its wholesale reform.

The report describes in chilling detail a department that is severely dysfunctional on every level: one that regularly uses excessive force on civilians, frequently fails to investigate serious crimes and has a deeply inadequate, in many cases nonexistent, system of accountability.

Using the report as a guideline, federal and local officials will now enter into negotiations leading to a consent decree, a blueprint for systemic reform that will be enforced by a federal judge.

“There is nobody in this room that is surprised by the general tenor and the tone of what this report has to say,” said Mitch Landrieu, the mayor of New Orleans, at a news conference attended by city and federal officials.