The cost of tackling major crime in Nottinghamshire has gone £500,000 over budget in the first half of the financial year.
Police say the overspend is the result of an inquiry into a street fight in St Ann's in September in which one man was killed and another seriously injured.
The cost of a number plate tracing scheme has also proved too high.
The finances are to be discussed by Nottinghamshire Police Authority at a meeting on Wednesday.
The investigation into the massive brawl has already cost the Major Crime Unit nearly £300,000 and an extra £200,000 has been used on interpretors and police surgeons.
The number plate recognition system which links vehicle registration numbers to known offenders has gone £190,000 over budget.
The report said other parts of the Nottinghamshire force are likely to spend less than planned between now and the end of the financial year.