Terrifying video: Accused killer aims at cop, pulls trigger — but gun doesn't fire. It's his final mishap.

Officer Brianna Tedesco was on patrol about 5 a.m. July 26 near the Lakemoor (Illinois) Golf Club when she noticed an SUV backed into a gravel path with its lights off, the Chicago Tribune reported.

So Tedesco turned on her emergency lights — as well as her dashboard camera and body camera — and shined a light into the vehicle, the paper said.

Image source: Lake County State's Attorney video screenshot

The man in the driver's seat had been lying back in it, and he told Tedesco his name was James Dunkin and that he was from Pennsylvania and was traveling west, the Tribune noted.

The officer asked him for ID.

"I just have to make sure, you know, you don't have any warrants or anything — which I'm sure you don't," Tedesco was heard saying on her bodycam clip, which authorities just released this week.

Ah, but the guy most certainly did have warrants.

Uh oh

Turns out his real name was Kenneth Martell, and he was wanted in Pennsylvania for beating and stabbing to death an 88-year-old man.

And as Tedesco was speaking on her radio next to Martell's driver's side door, the video showed him pulling a gun on the officer, who started screaming.

Image source: Lake County State's Attorney video screenshot

Martell pulled the trigger, the Tribune said — but the gun didn't fire.

Image source: Lake County State's Attorney video screenshot

Tedesco and Martell struggled for control of the gun over the next 20 seconds, the paper said, as the officer repeatedly screamed "no!" and "please don't shoot me!" Martell also attempted to grab a second gun, WPVI-TV reported.

Image source: YouTube screenshot

Another cop shows up

In a nick of time, fellow Lakemoor Officer Anthony Loiacono showed up to the scene, pulling up behind Tedesco's squad car, the Tribune said, adding that he could hear Tedesco's screams even with his windows up.

Image source: Lake County State's Attorney video screenshot

The paper said the suspect raised both of his hands — each holding a weapon — and Loiacono fired at him.

Image source: YouTube screenshot

Martell was struck in the head and died, the Tribune reported, adding that an autopsy found the 36-year-old Springboro man had amphetamine, methamphetamine, and marijuana in his system.

More from the paper:

Authorities launched a search for evidence in the nearby woods. Police found a large number of weapons, including rifles, shotguns, ammunition and crossbows; court documents, bail bond documentation and a criminal summons for Kenneth Martell; stolen property and identification cards of Theodore Garver, the man found dead in Pennsylvania.

Authorities said Martell beat and stabbed Garver to death during a robbery in Crawford County three days earlier, GoErie.com reported.

What did the Lake County state's attorney have to say?

Lake County State's Attorney Michael Nerheim released a report last month stating that an investigation and review determined that the Martell shooting was justified, the Tribune reported, and that the officers feared for their lives.

"Both officers were heroes as far as I'm concerned — they way they handled it from beginning to end," Nerheim said Tuesday after his office released the bodycam and dashboard camera videos to the public on its website, the paper added.

"It's a really dramatic video. The first time I saw it, I felt my heart beating through my chest," he noted, according to the Tribune. "It's hard to watch."

More from the Tribune:

In a report on the shooting, Nerheim concluded that "retreat was not an option. With both officers within feet of a man armed with two handguns, only one option remained for the officers: To defend themselves."

He said Tedesco's "quick actions and fight for the gun allowed additional time for her partner to arrive at the scene. Her partner was then able to end this deadly confrontation. The acts of these two skilled officers were masterful and indicative of two people acting in self-defense."

Nerheim also noted how valuable video evidence was in this case.

"This is the good thing about police departments getting body cameras. In past, there was no footage," he added to the Tribune. "This highlights how incredibly dangerous their job is."

(H/T: Blue Lives Matter)