Roanoke, Virginia — A manhunt is intensifying for a Marine deserter charged with homicide. The search for 22-year-old U.S. Marine Michael Alexander Brown prompted schools and some businesses to close in Roanoke, Virginia.

"We consider him to be armed and dangerous at this time," said Police Chief Tim Jones.

Brown went AWOL last month, abandoning his post at North Carolina's Camp LeJeune. Police said he returned to his home outside Roanoke, where they believe he shot and killed his stepfather. No motive is known.

On Thursday, Brown was seen outside his grandmother's house in Roanoke and police found an RV belonging to him nearby. They rammed it repeatedly with an armored vehicle but Brown was not inside.

Fearing he might still be in the area, authorities closed all 28 Roanoke public schools and some businesses and urged residents to be vigilant.

"He certainly trained with weapons, he knows how to use them, he has United States Marine Corps training, so we don't want to push him," Jones said.

The FBI is assisting in the hunt for Jones, and on Thursday, the bureau issued a wanted poster.

"I think that's very possible that he could sustain himself indefinitely in the area around southwest Virginia. It's very wooded, very mountainous," Jones said.

Jones said he's hoping family members and friends can convince Brown to simply turn himself in. As for the Roanoke schools, Jones said they will reopen Friday.