A new academic study that builds on Washington Post research into fatal shootings by police has found that unarmed black men were shot and killed last year at disproportionately high rates and that officers involved may be biased in how they perceive threats.

The study,“Fatal Shootings By US Police Officers in 2015: A Bird’s Eye View,” was conducted by criminal justice researchers from the University of Louisville and the University of South Carolina. It is being reviewed for academic publication and will be shared this week with members of the Major Cities Chiefs Police Association, which includes officials from departments in the 50 largest cities and metropolitan areas.

In 2015, The Post documented 990 fatal shootings by police, 93 of which involved people who were unarmed. Black men accounted for about 40 percent of the unarmed people fatally shot by police and, when adjusted by population, were seven times as likely as unarmed white men to die from police gunfire, The Post found.

Researchers, who used data collected by The Post, found that when other factors are considered, the racial disparity persists, but it is lower — twice the rate for unarmed black men compared with unarmed white men. Researchers adjusted for the age of the person shot, whether the person suffered from mental illness, whether the person was attacking a police officer and for the crime rate in the neighborhood where the shooting occurred.

“The only thing that was significant in predicting whether someone shot and killed by police was unarmed was whether or not they were black,” said Justin Nix, a criminal justice researcher at the University of Louisville and one of the report’s authors. “Crime variables did not matter in terms of predicting whether the person killed was unarmed.”

In the study, researchers wrote that their analysis of the 990 fatal shootings in 2015 “suggests the police exhibit shooter bias by falsely perceiving blacks to be a greater threat than non-blacks to their safety.”

Black individuals shot and killed by police were less likely to have been attacking police officers than the white individuals fatally shot by police, the study found.

“This just bolsters our confidence that there is some sort of implicit bias going on,” Nix said. “Officers are perceiving a greater threat when encountered by unarmed black citizens.”

The report noted that officers may unconsciously develop biases over time. “In other words, the police — who are trained in the first place to be suspicious — become conditioned to view minorities with added suspicion,” according to the report.

The authors said the findings have policy and practical implications, and researchers suggested that police departments should better train officers on how to reduce bias. The researchers also suggested that departments invest in body cameras to increase transparency.

The Post, relying on news reports and other sources, tracked in a database more than a dozen characteristics about each shooting, including whether the officer was under attack. The effort documented more than twice as many fatal shootings by police last year than had been reported on average annually in FBI statistics. The project is continuing and has identified more than 260 fatal shootings by police so far this year.

In the first three months of 2016, 12 percent of blacks killed were unarmed, compared with 6 percent of whites, according to The Post database.

“For the first time in history, the media has better data than the researchers,” said Geoffrey Alpert, a criminal justice professor at the University of South Carolina and one of the report’s authors. He said the lack of comprehensive federal data on police shootings and other deaths in custody is a national embarrassment.

Researchers said they conducted the study to better understand how to reduce the shootings by police of unarmed people. They said, however, that The Post data has limitations — it covers one year only and did not include information about non-fatal shootings by police.

“We’re trying to argue that the government should collect this data properly,” Alpert said. “They should be accounting for every bullet fired. We should know exactly why a cop pulls the trigger each and every time he or she does.”

Darrel Stephens, executive director of the Major Cities Chiefs Police Association, said he plans to send the published report to his member chiefs and that he has asked the researchers to present their findings at the group’s May membership meeting.

“Their work is very well done and provides insight into these incidents that was not available before [The Post] started collecting this data,” Stephens said in an email.