Several police killings of African-Americans, which sparked a year of nationwide protests under the Black Lives Matter social just movement, are missing from federal tallies because local police departments have refused to provide the data to officials, the Guardian reported Thursday. The missing cases include the police-involved deaths of Eric Garner in New York, as well as Tamir Rice and John Crawford in Ohio.

Only 224 of 18,000 U.S. law enforcement agencies reported fatal shootings by their police officers to the Federal Bureau of Investigation last year, according to the Guardian, which began keeping its own tally following high-profile cases in 2014. Previously unpublished FBI data highlights some flaws in official reporting systems, which government leaders have promised to reform to better track uses of force by police.

Stephen Fischer, an FBI spokesman, said the exclusion of police shooting cases happens because the federal reporting program is not yet mandatory. “We have no way of knowing how many incidents may have been omitted,” Fischer said.

Crowd-sourcing has allowed law enforcement watchdog groups to track killings, particularly when cases are ruled “justifiable homicides.” The available data submitted to the FBI by U.S. police agencies, spanning from 2004 through 2014, shows huge state-by-state disparities in reporting.

For example, not a single police department in Florida, the nation’s third-most populous state, reported police-involved homicides to the FBI. The New York Police Department, which has the nation’s largest force at over 13,500 officers, has submitted data for just one year during the past decade, according to the Guardian. Earlier this month, the NYPD released updated use of force policies that include new procedures for tracking and reporting the cases. 

High-profile cases reported in recent years were filed by police department in categories marked as “general homicides,” without a note that the subject was killed by police. Other police killings were ignored altogether.

Erica Garner, the daughter of the 43-year-old African-American man who died in 2014 after NYPD officers held him in a banned chokehold maneuver, told the Guardian she was “outraged but not shocked” by the omission of her father’s death from federal data. “It’s just another part of the cover-up and erasing of his murder from the record,” she said. “It says to the NYPD and the city and state of New York that my father’s life doesn’t matter.”