LOS ANGELES — For the Los Angeles Police Department, the allegations of departmental corruption and racism by a former police officer now accused of a revenge-fueled killing rampage are the words of a delusional man, detached from the reality of the huge improvements the force has undergone over the years.

“These are the rantings of a clearly very sick individual,” William J. Bratton, a former department commissioner, said Friday. “It would be a shame if he was able to rally to his cause people who remember the bad old days of the L.A.P.D.”

Yet for whatever changes the department has undergone since the days when it was notorious as an outpost of rampant racism and corruption, the accusations by the suspect — however disjointed and unhinged — have struck a chord. They are a reminder, many black leaders said, that some problems remain and, no less significant, that memories of abuses and mistreatment remain strong in many parts of this city.

“Our community doesn’t need this,” said the Rev. William D. Smart, the president of the Southern Christian Leadership Conference of Southern California. “We don’t need something like this opening old wounds.”