A Seattle man facing manslaughter charges for fatally shooting a car prowler with a rifle pleaded guilty Friday after reaching a plea agreement with prosecutors.

Filing a second-degree manslaughter charge in September, King County prosecutors alleged that Douglas Cameron Sheets acted with criminal negligence when he shot Jhovany Hernandez outside his Northgate home. According to court filings, police came to believe that Sheets shot Hernandez as the 21-year-old fled.

Sheets was arraigned Friday, then pleaded guilty to second-degree manslaughter. Since he has no other criminal record, he would face a sentence of 21 to 27 months.

But prosecutors will recommend just nine months, pointing to a mitigating factor listed in sentencing laws. That factor is invoked when the victim instigated the incident as Hernandez did during the car prowl.

Describing the Sept. 24, 2008, shooting, Seattle police Detective James Cooper said in statements to the court that incident began when Sheets heard several men breaking into his car.

From the balcony of his apartment in the 9700 block of Fifth Avenue Northeast, Sheets saw an unfamiliar car idling near the parking stall underneath the balcony where his Toyota Camry was parked. Three other men, Cooper said, were breaking into the vehicle.

Sheets returned to the balcony with a Mosin-Nagant bolt-action rifle, Cooper said, prompting the men in the car to flee as two of the apparent car prowlers, including Hernandez, remained near the apartment. Trying to get to the prowlers' car, Hernandez ran carrying a 27-pound subwoofer taken from Sheets' car.

Cooper said that Sheets told officers Hernandez turned and reached for the waistband of his pants before the shooting. Sheets took aim and fired, striking Hernandez in the back of the head.

Sheets then rushed out of his apartment, Cooper said, checking Hernandez for a pulse and found the man dead. Police later determined that Hernandez was unarmed at the time of the shooting.

Speaking to officers after being taken into custody, Sheets allegedly told investigators he had not intended to kill Hernandez.

"When the defendant told them to freeze, the defendant claimed the last guy turned around holding the subwoofer up by his head with one hand," Cooper said in court documents. "The defendant said (Hernandez), with his free hand, then started reaching for his waistband."

Sheets, the detective added, "said he wasn't going to take any chances, he 'freaked the (expletive) out, and he fired."

During an autopsy, staff with the King County Medical Examiner's Office found Hernandez had been killed by the single gunshot to the back of his head.

Sheets will likely be sentenced in about a month.