The brother and girlfriend of a man wanted for killing a Tennessee police deputy and wounding a second have been arrested as the manhunt for the suspect enters its fourth day on Monday.

Kenneth DeHart, 42, is accused of fatally shooting Blount County Sheriff's Deputy Greg McCowan, 43, and injuring Deputy Shelby Eggers, 22, during a traffic stop in Maryville on Thursday evening.

DeHart's brother, 41-year-old Marcus DeHart, has been arrested and accused of being an accessory for aiding the suspect after the homicide, Blount County District Attorny Ryan Desmond announced Friday. The brother was jailed, and Desmond said he faced a Monday court appearance. 

A woman identified by media outlets as the shooting suspect's girlfriend, 32-year-old Carrie Mathews, was arrested Thursday night on her own "accessory after the fact" charge in adjoining Sevier County, where records show she was jailed Saturday.

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Kenneth DeHart traffic stop

Kenneth DeHart, 42, remains on the run after allegedly killing a sheriff's deputy and wounding another during a traffic stop. (Blount County Sheriffs Office)

Following the two arrests, authorities encouraged the public to come forward with information about DeHart’s whereabouts, increasing the reward to $100,000.

"Somebody knows where he’s at. Somebody is protecting him," Tennessee Bureau of Investigation (TBI) Director David Rausch said Sunday. "My question to them is why?"

Kenneth DeHart

The manhunt for DeHart entered its fourth day on Monday. (Tennessee Bureau of Investigation)

The deputies had initiated a traffic stop on a sport utility vehicle for suspicion of erratic driving when the driver, identified as DeHart, refused to leave the vehicle, TBI said in a news release. The deputies deployed a stun gun to no effect.

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At some point, the driver produced a gun and opened fire, striking both deputies, according to the agency. At least one deputy returned fire while DeHart drove away from the scene.

Deputy Greg McCowan and Deputy Shelby Eggers

Deputy Greg McCowan was shot and killed during a traffic stop Thursday evening, and Deputy Shelby Eggers was wounded. (Blount County Sheriff's Office)

McCowan, who began his full-time career at the sheriff’s office in 2020 after working as a reserve deputy, was pronounced dead at a hospital.

Warrants have been issued for first-degree murder, attempted first-degree murder and felon in possession of a firearm in the manhunt for DeHart.

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"We’re going to turn every rock over," Rausch said. "We’ll find him, there’s no doubt." 

The Associated Press contributed to this report.