Residents of Ferguson, Mo., the St. Louis suburb that became known two years ago as a focal point of racial upheaval, voted on Tuesday to reject part of a tax increase package that city leaders had described as essential for carrying out a legal settlement with the Justice Department. The voters turned down a proposed property tax increase, but they also voted to raise the sales tax, leaving city officials with a mixed, uncertain result.

Leaders in Ferguson agreed last month to overhaul their Police Department and courts as part of a deal with federal authorities who found the city’s law enforcement system tainted by bias after a white Ferguson police officer fatally shot an unarmed black teenager in 2014, setting off a national debate over race and police conduct.

Mayor James Knowles III has said the tax increases are needed if the city is to carry out all its promises of added training, oversight and data analysis of the police and the courts. Ferguson officials have said meeting the terms of the federal settlement may cost as much as $1.5 million in the first year, as much as $880,000 in a second year and as much as $750,000 in a third year.

It was unclear late Tuesday whether the sales tax increase alone will be sufficient, and Mr. Knowles has said city officials will need to further analyze the mixed outcome to decide how the city will proceed. Local election results were slow to be counted in St. Louis County after problems getting ballots at numerous precincts delayed some polls from closing and caused confusion around the region.