Jacksonville, N.C. — A Camp Lejeune Marine suspected in the death of a pregnant comrade has been added to the FBI Most Wanted list, and the agency on Monday posted a $25,000 reward for information leading to his arrest.

A "massive, fugitive manhunt continues" for Cpl. Cesar Armando Laurean, 21, who has been charged with murder in the slaying of Lance Cpl. Maria Lauterbach, 20, who had accused him of rape, authorities said. Burned human remains, believed to belong to Lauterbach and her unborn child, were found Saturday in a pit in Laurean's back yard.

Laurean also is wanted on a federal warrant charging him with unlawful flight to avoid prosecution.

Digital billboards bearing Laurean's picture went up Monday in his hometown of Las Vegas and in Columbus, Ohio. Other billboards were being posted nationwide, authorities said.

The search for Laurean is "earth-wide," Onslow County Sheriff Ed Brown said Monday, adding that anyone who spots Laurean should call their local police and should not try to detain him.

"It's not worth getting hurt over. It's evident he will hurt you," Brown said.

FBI spokesman Newsom Summerlin said investigators have no reason to believe Laurean has fled the country, but that it is possible.

Brown also said Monday that an ATM card belonging to Lauterbach was found Saturday in Durham. A jogger passing by a Greyhound Bus station downtown noticed it in the bushes and turned it over to Durham police.

Police said it was unlikely the card was used at the bus station because the card reader there has been out of operation for several days.

Investigators remain unsure of the accuracy of witness reports placing Laurean at a bus depot in Shreveport, La., on Saturday night, Brown said. The witnesses were unclear whether the man believed to be Laurean boarded a bus that was headed to Texas or left the station, he said.

Still, Brown confidently predicted that Laurean would be caught.

"You're never gone for good when law enforcement is after you," he said. "It may be two days or two weeks, 10 days or 10 years, but you're never gone for good."

The possible sightings came the same day that authorities recovered burned remains from a fire pit in Laurean's back yard. The remains were sent to the state Chief Medical Examiner's Office in Chapel Hill on Monday for a positive identification and to determine the cause of death.

Lauterbach disappeared sometime after Dec. 14, when she last spoke on the telephone with her stepmother in Ohio. Mary Lauterbach reported her stepdaughter missing five days later.

The Marines immediately placed Maria Lauterbach on "unauthorized absence" status and placed her name in a national law enforcement database as a "missing person at risk."

Her disappearance came not long after she met with military prosecutors to talk about her allegation that Laurean raped her last April. Naval investigators said Saturday that the rape case was progressing and that a protective order had been issued to keep Laurean away from Lauterbach.

Military investigators said they didn't consider Laurean a threat to Lauterbach, however, or later a flight risk, because they had indications the pair were on friendly terms.

Brown said the military didn't give his investigators Laurean's name until weeks after Lauterbach disappeared.

"At that time, it was not even an issue they felt important enough to bring to the attention of (the Naval Criminal Investigative Service)," he said.

Laurean then refused to meet with Onslow County investigators and left town without telling his lawyers where he was going.

Camp Lejeune officials released a brief statement Monday saying that the base command was reviewing the case to determine what information was available to commanders and when it was available.

Lauterbach's cell phone was found along a highway near Camp Lejeune on Dec. 20, and her car was found a week ago outside a bus station nearby.

Authorities said they believe Laurean fled Jacksonville before dawn Friday in a 2004 black Dodge pickup truck with North Carolina license plate TRR-1522. He left behind a note in which he said he buried Lauterbach's body after she committed suicide by cutting her throat.

Laurean's wife, Christina, confronted her husband before he fled and urged him to tell his story to police, Laurean's father-in-law, Bruce Shifflet, told CBS News on Monday.

"Christina definitely got on him to turn himself in," Shifflet said in an interview on the CBS Early Show. "(She) told him he needed to take responsibility for these actions and not run, so that this wouldn't become just chaos for the family."

Christina Laurean, a former Marine, has been devastated by the allegations against her husband and his subsequent disappearance, her mother said. Debbie Shifflet added that her daughter is concerned about the impact the episode will have on the Laurean's' 18-month-old daughter.

Bruce Shifflet said the family is finding it harder to believe Cesar Laurean's version of events as time goes on.

"I kind of almost wanted to believe that myself, too, because, having met with Cesar, his character doesn't (indicate) that at all. He's a very personable, likable guy who our family enjoyed being around," he said.

He urged his son-in-law to surrender for his family's sake.

"I thought he was a man of character, but it's obvious he's just a coward, taking off on his family and leaving this as a tragedy for both families," he said. "It's just a horrible, vulgar act."

Brown has challenged Cesar Laurean's assertion that Lauterbach killed herself, citing what he described as evidence of a violent confrontation inside the Laurean home – blood spatters on the ceiling and a massive amount of blood on the wall. Someone apparently tried to clean up the blood, even painting over some of it, he said.

Neighbor Wanda Alander said she noticed paint cans stacked on the porch of the Laurean home before Christmas.

"When I went over there, the living room was already painted. (Christina Laurean) mentioned that they were going to do some more stuff, like paint the bedrooms and the garage," Alander said.

Alander also said she saw the couple burning something behind the house around the same time, while her husband claimed he saw Cesar Laurean driving Lauterbach's car.

Christina Laurean, who delivered her husband's note to authorities on Friday, has cooperated with the investigation, Brown said.

Brown has said Lauterbach purchased a bus ticket to El Paso, Texas, around the time of her disappearance and did not use it, but he said Sunday authorities do not have the ticket. Shreveport is roughly 950 miles southwest of Jacksonville, about two dozen miles from the Texas state line and more than 800 miles east of El Paso.

Shreveport police Chief Henry Whitehorn Sr. said his department was working with the U.S. Marshal's Service and other law enforcement agencies to locate Cesar Laurean.

"We don't know if he is still in the area," Whitehorn said. "We believe it may have just been a pass-through."