Jacksonville, N.C. — Authorities issued an arrest warrant Saturday for a Marine corporal wanted in the death of a pregnant colleague, whose burnt remains were excavated from a fire pit in his backyard.

Onslow County Sheriff Ed Brown said investigators also recovered the remains of Lance Cpl. Maria Frances Lauterbach's unborn child.

"The fetus was developed enough that the little hand was about the size of my thumb," Brown said. "The little fingers were rolled up and this is consistent with what we were looking for, a pregnant lady who is the victim, Maria Lauterbach, and her unborn child."

A nationwide search is under way for Marine Cpl. Cesar Armando Laurean, who authorities said fled Jacksonville early Friday morning after leaving his wife a note in which he admitted burying Lauterbach's body.

"We will do everything within our power to see that justice prevails in this case,” Onslow County District Attorney Dewey Hudson said.

Lauterbach had accused Laurean of rape, and authorities have described a violent confrontation inside his home that left blood spatters on the ceiling and a massive amount of blood on the wall. It appeared that someone had tried to wash and paint over the blood, Brown said.

Authorities said late Saturday that they think they have found the murder weapon, but were not saying yet what it was.

Lauterbach, 20, disappeared in December, just days after meeting with military prosecutors to talk about the rape allegations. Her remains were found in a fire pit in the backyard of Laurean's home, buried up to a foot in ashes and dirt, said Dr. Charles Garrett, the county medical examiner.

Garrett and Brown said the remains will be sent to the state medical examiner's office in Chapel Hill for a formal identification using dental records.

"As well as I could see, the body was much charred," Brown said. "The fetus was in the abdominal area of that adult. ... That is tragic, and it's disgusting."

Laurean's note said Lauterbach had "come to his residence and cut her (own) throat," Brown said. He confirmed Saturday that authorities received the note Friday from Laurean's wife, Christina, about four hours after they suspect he fled.

Laurean wrote in the note that he had nothing to do with Lauterbach's suicide, but that he had buried her body, the sheriff said.

Authorities have dismissed the idea that Lauterbach killed herself, pointing to the blood stains and the obvious signs of a cleanup inside Laurean's one-story, brown brick ranch home. Brown challenged Laurean, who has not been charged with a crime, to come forward and defend his claims of innocence.

Brown declined to say whether authorities thought Christina Laurean had a hand in Lauterbach's disappearance.

She is "heartbroken," said her mother, Debbie Sue Shifflet.

"I feel sorry for the other family," Shifflet said. "It's horrible what they're going through. My heart goes out to them."

Brown said there had been no sightings of Laurean, 21, of the Las Vegas area. He had refused to meet with investigators and left without telling his lawyers where he was going, the sheriff said.

The State Bureau of Investigation and the Marine Corps are assisting in the search for Laurean. He is believed to be driving a black 2004 quad cab Dodge pickup with North Carolina tags TRR-1522.

"We are marching forward to answer every question we can about this investigation," Brown said.

Lauterbach met with military prosecutors last month to discuss pursuing rape charges against Laurean, said Kevin Marks, supervisory agent with the Naval Criminal Investigative Service at Camp Lejeune. He said military prosecutors believed they had enough evidence to argue that the case should go to trial.

In court papers filed this week, authorities said the anticipated birth of the baby "might provide evidentiary credence to charges she lodged with military authorities that she was sexually assaulted." Lauterbach reported the rape in April and was due to give birth in mid-February, authorities said.

Lauterbach apparently described the attack to former Marine and roommate Melinda Artzer.

"She proceeded to tell me that she was walking home at night and someone came out of the dark and attacked her,” Artzer said.

Outside the family's home in Vandalia, Ohio, Lauterbach's uncle, Pete Steiner, said the rapist was the father.

Authorities said they had not been concerned that Laurean would flee because they had information he and Lauterbach carried on a "friendly relationship" even after she reported the assault to military authorities. There is no indication Lauterbach asked the military to protect her after she leveled the rape allegations, investigators said.

Steiner, however, said his niece didn't have any kind of relationship with her attacker, and that Lauterbach had been forced to rent a room off base because of harassment at Camp Lejeune.

"She was raped," Steiner said. "The Marines, unfortunately, did not protect her, and now she's dead."

Originally from Dayton, Ohio, Lauterbach was reported missing December 19 by her mother, who last spoke with her daughter on December 14, authorities said. Her cell phone was found December 20 near the main gate at Camp Lejeune, and she missed a December 26 prenatal care appointment.

Lauterbach, who joined the Marines in 2006, and Laurean were personnel clerks in the 2nd Marine Logistics Group of the II Marine Expeditionary Force, based at Camp Lejeune. Neither had been sent to Iraq or Afghanistan.