While much of the nation’s attention is focused on the aftermath of a grand jury’s decision not to indict Ferguson police officer Darren Wilson in the Aug. 9 shooting of Michael Brown, the United States has witnessed police-involved violence resulting in the shooting deaths of at least 12 people across the country in just the last week.

The Cleveland police shooting death of 12-year-old Tamir E. Rice on Nov. 23 sparked outrage and national attention after it appeared that the child was shot after brandishing a BB gun. While in New York City, the accidental shooting death of Akai Gurley, 28, by an NYPD officer patrolling a stairwell in a Brooklyn public housing unit has also provoked public indignation.

Other police-involved shooting deaths from Monday, Nov. 17 to Sunday, Nov. 23 occurred in California, Arizona, Florida, New Jersey and Utah. According to the Salt Lake Tribune, more people have died in Utah due to police shootings in the last five years than violent deaths at the hands of gang members and drug dealers.

The FBI does not release annual data on how many Americans are killed by law enforcement officers — information that activists who mobilized after the Ferguson shooting in August have demanded of the Obama administration.

Although Al Jazeera identified 12 incidents of deadly police force over the span of seven days, the number of actual incidents may be higher. Killed By Police, a Facebook page that posts links to news reports of homicides by law enforcement, found 23 incidents during the same timeframe.

But even that number seems low, says D. Brian Burghart, editor of Reno News & Review, who founded Fatal Encounters, a project compiling comprehensive and searchable national data of people killed by law enforcement officials.

The Uniform Crime Reports (UCR), official national crime data complied annually by the FBI, indicates that there were 461 total deaths at the hands of law enforcement in 2013, the most recently published year. But Burghart told Al Jazeera that after scanning local government agencies and media reports the number of police-related fatalities was “closer to about 1,400 a year,” with at least 9,000 from 2000 to 2014.

Over 18,000 law enforcement agencies — including city, county, state and federal law enforcement departments — voluntarily participate in sharing crime data with the FBI. However, only 750 of those agencies contribute to UCR’s data on law enforcement-related incidents, leaving a gap in the fatalities reported by UCR versus the actual number of incidents.

Samuel Walker, a professor of criminal justice at the University of Nebraska and author of In Defense of American Liberties, told Al Jazeera that the problem of reporting police-cause fatalities remains "the failure of the FBI and the Justice Department to insist that all agencies report this data."

"Officers assaulted and killed by citizens — well they're very eager to collect and report that data, but they don't report the other side of the equation," said Walker.