In footage from Taylor's body camera, he can be heard repeatedly asking Barker's name, saying neighbors reported his behavior was suspicious. After a brief, relatively calm conversation, Barker can be seen growing agitated and shouting at Taylor.
The encounter went from "zero to 100," as Barker yelled and stuck a finger in Taylor's face, as Taylor later described in a police interview.
As Taylor can be seen in the footage moving forward to go "hands on" and try to cuff Barker, the officer later told investigators Barker jumps back and swings the shovel at Taylor, disabling the body camera.
Taylor said he fell off the porch and realized his arm was broken, according to a report released Monday by District Attorney Sim Gill. Taylor said he grabbed his Taser because he couldn't reach his gun. But Barker "jumped on him" and hit the Taser out of his hand, Taylor told investigators.
Barker also grabbed at Taylor's "gun or holster at least twice," Taylor said.
"I know if he gets my gun, he's going to kill me," Taylor said, noting that he was especially concerned that Barker hadn't fled after knocking Taylor off the porch.
"I've had guys fight me, but they run away," Taylor told investigators. "When I got knocked off, [Barker] had plenty of time to run away. He's still coming ... grabbing for my gun. His one goal was to try and kill me."
Taylor said he pushed Barker off him and drew his gun, shooting Taylor three times from a "couple of feet away."
Eyewitnesses supplemented Taylor's account.
Richard Grow, who lives in the northwest corner of the Avenues, witnessed the final moments of the struggle between Taylor and Barker.
Grow, 66, was driving south on I Street when, as he approached 2nd Avenue, he saw the two men leap off a front porch, one after the other. In an interview with The Salt Lake Tribune, he said he is not sure if the officer was the first one off the porch; he initially thought they were two roommates fighting and only later realized that one was a policeman.
By the time Grow pulled up, stopping his car about 40 feet from the fight, the two men were wrestling on the ground in front of the house.
"They wrestled on the ground for 10 to 15 seconds," Grow said. Then he saw the officer "reach around his side and pull out his gun and hold it up to the guy's chest and bam, bam, bam. ... point-blank against this man's chest."
Grow got out and asked the officer, who Grow thought looked haggard, if he needed any help.
"He just said, 'Get out of here,' " Grow said. He obeyed, but filled out a statement at police headquarters a few hours later.
Grow said he never saw a shovel, but added that anything involving the implement may have happened beforehand.
Another witness, identified in Gill's report as "K.M.," was driving north on I Street when she saw a man hitting a police officer seven to 10 times with the snow shovel, investigators wrote.
K.M. said the officer was being "beat down the stairs," and that the officer ended up in a "crouched position" with his "arm up in a defensive position."
The man was "beating [Taylor] so hard," and that she saw the snow shovel break during the assault, K.M. said. Investigators found "plastic blue pieces of the shovel strewn about the front yard," Gill wrote.
"Officer Taylor was involved in a situation in which he reasonably believed his life was in danger," Gill said in the report. "After Barker hit him with a snow shovel and continued to fight with Officer Taylor on the ground, [Barker] knocked the Taser out of Officer Taylor's hand and pulled on Officer Taylor's gun."
The Salt Lake Police Association has said the video shows justification for lethal force. SLPA President Michael Millard has said the officer had been professional and respectful and acted reasonably.
Friends and neighbors of Barker have said the officer should have tried to de-escalate the situation. The shooting prompted an online petition by former Salt Lake City Councilwoman Deeda Seed, demanding more officer training in de-escalation, mental illness and communication skills. It has gathered more than 1,000 supporters.
Barker's friends called him an artistic nature-lover, musician and surfer, who volunteered at community arts events and quit his church basketball team because it was "too violent."
"He was one of [Jack] Kerouac's bright, burning roman candles," said Summer Osburn, who became friends with Barker 20 years ago while they were students at Brigham Young University.
Barker's girlfriend has said she asked him to break up ice that had packed around a bus stop on the shaded north side of their home Jan. 8. He evidently took the snow shovel and began walking through the neighborhood, apparently soliciting future work.
The 911 call recording was released earlier this month by the Salt Lake City Police Department after an open-records request from The Tribune.
"The other day, this guy I'm 95 percent sure it's the same guy he was looking in cars," the caller, identified as R.H. in the district attorney's report, tells a dispatcher. " ... He's walking my neighborhood today looking for people [to] shovel their walks. ... He is carrying a snow shovel door to door. And it's not snowing, you know?"
Other neighbors said the caller apparently did not know Barker, who occasionally did odd jobs for cash or trade.