EL PASO, Texas -- Investigators believe they have found the shallow grave with the burned remains of the pregnant marine in the back yard of a comrade she had accused of rape.

The search for Lance Cpl. Maria Lauterbach's body centered on a coastal neighborhood, near Camp Lejeune, N.C., where she was stationed.

Ed Brown, sheriff of Onslow County, said the case moved from being a search for a missing person to a murder investigation after a witness came forward with some key information about the missing Marine.

“That Ms. Lauterbach is dead and has been buried here on Onslow County; the suspect in the case is the marine who was accused of assaulting her, " Brown said.

That Marine, and now suspected killer, is Cpl. Cesar Armando Laurean.

Lauterbach accused him of raping her and was days from testifying against him when she disappeared.

Now, officials believe Laurean is on the run.

"He's out of town; he's gone," Brown said.

Authorities believe the suspect fled the area in a black, two-door pickup truck.

Lauterbach's family last heard from her on Dec. 15, when she bought a ticket for a bus bound for El Paso.

She was due to give birth any day.

Brown added, “I had my insides knocked out with this negative information. I was about to cry."

Investigators believe the suspect fled early Friday morning, giving him at least an eight-hour head start on police in Jacksonville, N.C.

At this point, officials don't know why Lauterbach bought a bus ticket for El Paso.

Many of the new details about her case came out in a police news conference on Friday.