Mayor Bill de Blasio and Police Commissioner Bill Bratton speak at police headquarters about the investigation into an axe-wielding attacker who injured two police officers in Jamaica, Queens Thursday afternoon.� View Full Caption DNAinfo/Ben Fractenberg

NEW YORK CITY — The NYPD's statistics released to the public about the number of murders, rapes, robberies, assaults and other major crimes are consistently off by as many as 229 incidents per month, DNAinfo New York has found.

The NYPD’s CompStat figures, which the department presents to the public each week, are regularly cited as an accurate measure of the city's safety.

However, when the numbers released each week by precinct and by crime category are added up and compared to the statistics the NYPD releases for its 28-day total for the same time period, the numbers often don't match, DNAinfo found.

The revelation comes on the heels of 19 officers in The Bronx being disciplined for underreporting crime numbers.

While the overwhelming majority of the adjustments were upwards — meaning the department added more incidents to the citywide total between the weekly and monthly roundups — in other instances, the number of crimes went down.

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DNAinfo examined the period between Dec. 14, 2014 and June 21, 2015.

In the 28-day period ending Jan. 25, the NYPD presented 7,625 incidents for the seven major crimes as part of its weekly CompStat reports. But when the NYPD presented its 28-day tally for citywide major crimes, the total was 7,396 — at least 229 major crimes lower than the numbers originally released.

The NYPD's monthly tally of crimes changed across the board, with three fewer rapes than in its weekly crime stats, one additional murder, 45 fewer felony assaults, 29 fewer robberies, 24 fewer burglaries, 93 fewer grand larcenies and 36 fewer car thefts, data show.

The opposite trend happened during the 28-day period ending March 22. The NYPD's 28-day total was 6,772, while a manual count of its weekly totals came to 6,720 — meaning the NYPD added 52 more crimes.

That included 29 more felony assaults, 11 more robberies, 18 more burglaries, one more rape, six more grand larcenies and 13 less car thefts.

The fluctuations continued throughout the first six months of this year, crime stats show.

DNAinfo found that the total monthly crime numbers were off by an average of less than 1 percent, which did not alter the macro portrait of crime in the city.

However, in certain individual crime categories, the difference was upwards of 3 percent, data show.

For example, during the 28-day period ending April 5, the number of car thefts went down by 4 percent as the NYPD reported 23 fewer incidents in its final tally than the 491 incidents it initially included in weekly roundups.

During the 28-day period ending May 3, felony assaults went up approximately 3.2 percent from initial numbers. The NYPD's 28-day total for felony assaults was 1,435 — 42 more than the 1,393 it had presented in weekly reports.

The NYPD's total for robberies in the 28-day period ending April 5 was 1,087 — up 2 percent from the initial 1,065.

The department recently cracked down on 19 officers in The Bronx's 40th Precinct after officials found they were underreporting crime stats.

The officers were found to have failed to properly process 55 complaints during a four-month period in 2014, mainly in the categories of petit larceny, lost property, misdemeanor assault, criminal mischief and criminal trespassing, officials said.

As a result, the precinct appeared to be experiencing a 14 percent decline in crime, when in fact crime had only dropped by 11 percent.

“The purposeful misrepresentation of crime data is rare but nevertheless unacceptable and it will be dealt with accordingly," Bratton said on Friday, pointing out how the NYPD relies on its stats to deploy resources and shift strategies.

"These disciplinary charges are strict but fair."

When asked to comment on DNAinfo's analysis of crime statistics, officials at the NYPD said the changes are within normal margins of error considering that the NYPD handles roughly 100,000 complaints each year involving serious crimes and another million in misdemeanors and lesser violations.

Officials explained that while they could not discuss individual cases, the reason crime numbers typically shift is because officers may have failed to properly identify the correct crime category, or investigators may have later uncovered evidence that required a shift to another classification.

“The numbers change back and forth every week when the complaints get a closer look,” said Inspector Paul Dentremont, commanding officer of the NYPD's Deputy Commissioner for Operations office.

“Sometimes, 40 complaints are changed to a higher category while 30 others are reduced to a lesser category, and it can go either way.

“The numbers change in all sorts of ways. Burglaries will be a robbery and a larceny will be a burglary and vice versa.”

For example, the inspector said that a motorist might report his car stolen and later find that a relative drove it somewhere without permission.

He added that the NYPD has several layers of checks-and-balances in place to ensure complaints are accurately recorded and to deter commanders from fudging numbers.

Under NYPD regulations, after an officer takes a complaint, precinct desk officers are expected to ensure its accuracy. They speak with the officers to confirm the category or make a change.

Each precinct also has a “crime analysis” sergeant who is tasked with reviewing complaints as part of the “integrity” process, and his or her changes may take days to catch up with the NYPD's databanks.

Finally, the NYPD has a “Quality Assurance Unit” that randomly checks hundreds of complaints as a further audit. The unit was primarily created to prevent commanders from cooking their numbers and to see if there are patterns where crime complaints are being under-reported.

When disparities are concentrated in certain precincts or part of the city, officials say a broader examination will likely be performed by the Quality Assurance Unit.

In the case of The Bronx's 40th Precinct, that system of checks and balances resulted in the discovery of the fudged numbers. Deputy Inspector Lorenzo Johnson, the commanding officer of the precinct, was removed from duty at the precinct and the NYPD brought disciplinary charges against 19 officers — including one lieutenant, eight sergeants, nine police officers and one detective, according to the NYPD.

Mayor Bill de Blasio — who staked his mayoralty on maintaining historically low crime numbers while improving police-community relations and de-emphasizing stop-and-frisk — also decried the actions of the 40th Precinct officers on Friday.

"The swift action taken by NYPD is testament to the department’s commitment to transparency and accountability," de Blasio's spokeswoman said in a statement.

"The only way to keep our city safe is to ensure police officers are accurately reporting criminal incidents."