In Pasco, Wash., officers fired 17 rounds that killed orchard worker Antonio Zambrano-Montes, who was armed only with rocks. At the Washington State Criminal Justice Training Commission, there is an increased focus on shifting the mentality of police officers from warriors to guardians. (Zoeann Murphy/The Washington Post)

On the afternoon of New Year’s Eve, Las Vegas police officers cornered Keith Childress Jr., who was wanted for a number of violent felonies. They opened fire on the black 23-year-old after he refused to drop the object in his hands, which turned out not to be a gun but a cellphone.

And with that, the nation logged what was probably its final police shooting death of 2015, a year in which 986 such killings occurred, well more than double the average number reported annually by the FBI over the past decade.

The shooting is the final one to be counted as part of The Washington Post’s year-long project tracking on-duty police killings by firearm, an issue that has taken on new urgency after a number of high-profile killings of unarmed African American men. The Post sought to document every shooting death at the hands of police in 2015, and it revealed troubling patterns in the circumstances that led to such shootings and the characteristics of the victims.

The project will continue this year. Federal officials have announced plans to improve their data collection, but the new initiative will not be in place until 2017. Already, The Post has tallied 11 fatal police shootings in 2016.

Over the past year, The Post found that the vast majority of those shot and killed by police were armed and half of them were white. Still, police killed blacks at three times the rate of whites when adjusted for the populations where these shootings occurred. And although black men represent 6 percent of the U.S. population, they made up nearly 40 percent of those who were killed while unarmed.

The Washington Post has investigated details surrounding those who died from police shootings, and here are six important takeaways.

Regardless of race, about a quarter of those killed displayed signs of mental illness. December was the fourth-deadliest month in 2015 for police shootings, with 89 fatal shootings. There was only one state without a fatal police shooting last year: Rhode Island.

The number of shooting deaths may yet rise for 2015. The Post is tracking a few cases in which it is unclear whether police gunfire killed someone or whether the person committed suicide. And new cases that have gone unreported could always emerge.

Childress’s death in many ways encapsulates the complex nature of these incidents. On one hand, the young man was unarmed, carrying nothing but a cellphone. At the same time, he had a history that suggested a capacity for violence, and he behaved suspiciously, ignoring officers’ commands for a full two minutes and advancing even as the officers threatened to shoot.

And like an increasing number of police interactions with citizens, the incident was partially captured on a camera worn by one of the police officers.

Two weeks before his death, Las Vegas police said, Childress failed to show up for a sentencing hearing in Phoenix. In December, a jury had convicted him of a litany of charges, including kidnapping and robbery in connection with a 2013 home invasion in which he and several others posed as bounty hunters and robbed people in a house at gunpoint.

“Based on the fact that Childress was facing a lengthy stay in prison, it appears he skipped the sentencing and fled to Las Vegas to avoid prison time,” Undersheriff Kevin McMahill of the Las Vegas Metropolitan Police Department told reporters in a briefing this week.

Childress was staying with close friends in Las Vegas when the U.S. Marshals Service became aware of his location, McMahill said. But when the marshals attempted to approach him, he fled, prompting the federal agents to seek help from local police.

While communicating with local police, however, the marshals conveyed incorrect information — that Childress was wanted for attempted murder, McMahill said.

About 2 p.m. local time on New Year’s Eve, two Las Vegas Metropolitan Police officers — Robert Bohanon, 37, and Blake Walford, 27 — arrived at the scene. Footage from Bohanon’s body camera shows the officers pulling into a residential neighborhood and happening upon Childress as he slowly crossed the street in dark clothing.

Bohanon drew his gun immediately. Over the course of about two minutes, Childress ignored 24 commands by the officers, McMahill said, all the while obscuring his right hand.

At some point, Bohanon remarks that there is “something” in Childress’s hand. Toward the end of the exchange, Bohanon screams at Childress not to “advance” on the officers. “Do not walk towards us,” Bohanon commands.

Just before the publicly available portion of the footage cuts out, Childress’s figure can be seen briefly walking toward the officers. It is then, McMahill said, that the officers opened fire, striking Childress five times.

He was pronounced dead at the scene. The object in his hand was later discovered to be a cellphone.

Bohanon, a sergeant, has been with the force since 1997, and Walford has been with the department since 2014, police said. Both officers are on routine paid administrative leave pending completion of the investigation.

In the news briefing, McMahill speculated that Childress might have been attempting to commit “suicide by cop.”

“An individual that’s being challenged by armed police officers and continues to walk toward them . . . certainly leads you to believe that he absconded from Arizona to come to Las Vegas, and he potentially just didn’t want to face the music for the charges down in Arizona,” McMahill said.

Childress’s death has provoked outrage from his friends and family, who believe vehemently that he should not have been killed.

“They just gunned him down,” said his mother, Jacqueline Lawrence, 45, a bank employee in Phoenix. “They said he had a gun, but he had a cellphone in his hand.”

Childress — a father of three who went by the childhood nickname Oompa — was taking college courses in business, Lawrence said. He had a passion for the outdoors, she added, and loved such activities as snowboarding and skydiving. He also had a generous streak.

“He was the type of person that his friends would go, ‘That’s a nice watch,’ and guess what he would do? He would give it away,” his mother said.

Photos on Childress’s Facebook page show a handsome if flashy young man with close-cropped black hair and copious tattoos, including a skyline on his chest and a vibrant rose on his right arm. Many of his friends have replaced their profile pictures with snaps of Childress, inscribed with the words “Justice for Keith Childress.”

Julie Tate, Jennifer Jenkins and Kimbriell Kelly contributed to this report.