(CNN) -- A grand jury has indicted a Marine for first-degree murder in the killing of a pregnant Marine colleague, the Onslow County, North Carolina, district attorney said Thursday.
The FBI has released this picture of fugitive Marine Cpl. Cesar Laurean with a tattoo on his left arm.
Authorities said they believe Marine Cpl. Cesar Laurean, 21, fled to his native Mexico after the death of Lance Cpl. Maria Lauterbach. One of Laurean's cousins said he saw the wanted man near Guadalajara, Mexico, a week ago.
Investigators said Laurean killed Lauterbach, 20, who was eight months' pregnant, last month, burned her body and buried it beneath a fire pit in his backyard. See a timeline of events »
Onslow County District Attorney Dewey Hudson said prosecutors will not seek the death penalty in the case if the suspect is found in Mexico but they are reserving the right to pursue that option if he turns up somewhere else.
Mexico will not extradite prisoners if they face a possible death sentence.
The grand jury also indicted Laurean on charges of ATM card theft, attempted card theft, fraud and robbery with a dangerous weapon.
Hudson said preliminary findings from a second autopsy performed on Lauterbach's body indicate that the slain Marine's fetus had not been born alive before her death.
"In North Carolina, the killing of a viable but unborn child is not against the law," Hudson said.
The military also is conducting further tests on a lung tissue sample to determine whether the fetus' lungs contained oxygen. If oxygen is found, it would mean the baby took a breath and would establish life. In that case, Laurean could face another murder charge.
Hudson said authorities are continuing tests to determine the paternity and gender of the fetus.
Lauterbach had accused Laurean of raping her.
Hudson submitted paperwork last week to the U.S. Justice Department to initiate action to apprehend Laurean in Mexico. Watch news of Marine's grand jury indictment »
Hudson said a Mexican judge has to sign off on a provisional arrest warrant.
Hudson said Wednesday the Marine autopsy involved some procedures not done by the state, including reconstruction of Lauterbach's skull. The state autopsy indicated that Lauterbach died from a blow to the head, contradicting a note Laurean left his wife saying that Lauterbach slit her throat during an argument.
Lauterbach was reported missing December 19, and her charred remains were found January 11 after Laurean's wife gave police the note from her husband. Laurean wrote that he was frightened and buried the body in the backyard.
The Marine's note said Lauterbach died December 15; authorities said they believe she was killed December 14.
Hudson also confirmed information from a law enforcement source that Laurean traveled by bus to Mexico. The source said he boarded a bus for Houston, Texas, on January 11, arriving the following afternoon.
In Houston, the source said, the Marine bought a bus ticket to San Luis Potosi, Mexico, probably arriving January 13 in Guadalajara.
In the nearby town of Zapopan, Mexico, Laurean stopped at a liquor store owned by his cousin Juan Antonio Ramos Ramirez. Ramos said that Laurean told him that he was traveling "with some buddies for a few days."
Hudson said, "It doesn't surprise me a relative would have seen him -- assuming he is telling the truth -- because Laurean has family in Mexico." E-mail to a friend
CNN's Susan Candiotti contributed to this report.