(CNN) -- The Marine accused of killing Lance Cpl. Maria Lauterbach, who was more than eight months pregnant, was not the father of her unborn child, a law enforcement source close to the murder investigation said Saturday.
Marine Cpl. Cesar Laurean, who is being held on a murder charge, is scheduled for arraignment in June.
The source, who has seen a report completed earlier this month by the Defense Department's Armed Forces Institute of Pathology, said Cpl. Cesar Laurean's DNA does not match that of the unborn child, who also died.
Laurean and Lauterbach were stationed at Camp Lejeune, North Carolina.
An autopsy showed that Lauterbach, 20, died of blunt force trauma to the head. Police unearthed her charred body from beneath a barbecue pit in Laurean's backyard in January 2008. She disappeared the month before.
Laurean was 22 when he was arrested in Mexico in April 2008. At the time, a Mexican reporter asked Laurean whether he had killed Lauterbach. The Marine replied, "I loved her." Laurean has been indicted on charges that include first-degree murder, financial card transaction fraud and obtaining property by false pretenses.
North Carolina prosecutors allege he killed Lauterbach on December 14 and used her ATM card 10 days later before fleeing to Mexico. He holds dual citizenship in the United States and Mexico.
The law enforcement source familiar with the case said a DNA swab was taken by court order from Laurean after he was extradited from Mexico in March to face charges in North Carolina. Mexican authorities agreed to the extradition, in part because prosecutors took the death penalty off the table. Mexico does not have a death penalty.
Before her death, Lauterbach told the Marines that Laurean raped her. The month before she disappeared, Lauterbach's mother says Maria told a military investigator that she no longer believed Laurean was the father of her unborn child. However, Lauterbach's mother, Mary, says her daughter remained adamant that Laurean raped her.
Laurean denied it. A few weeks before a scheduled rape hearing at Camp Lejeune, Lauterbach disappeared.
Dewey Hudson, district attorney for Onslow County, said Laurean is scheduled for arraignment in early June, and is expected to enter a plea.
"I cannot comment on any of the tests," Hudson said. He would not say how the DNA results might affect his case against Laurean.
Through her attorney, Mary Lauterbach said the DNA test results don't answer bigger questions she has about whether the Marines did enough to protect her daughter or moved quickly enough to investigate her claims.
"We do not believe that the result will have any effect on the continuing investigation or the trial," said Lauterbach's attorney Merle Wilberding.