The accused killer of U.S. government intern Chandra Levy is in the process of being transferred to Washington, D.C., to face murder charges, FOX News has learned.

Up until now, Salvadoran immigrant Ingmar Guandique, 27, has been an inmate at a federal prison in Adelanto, Calif.

The Bureau of Prisons Web site now says Guandique "in transit."

Federal Bureau of Prisons spokeswoman Felicia Ponce said Guandique was taken to the bureau's federal transfer center in Oklahoma City, according to The Associated Press.

Click here for photos.

It may be "a couple weeks" before Guandique actually arrives in the nation's capital city because of the complexity of prisoner transfers, a Department of Justice spokesman involved with the case told FOX.

Inmates are often sent temporarily to a middle-point federal prison — many times, to the one in Oklahoma — before winding up at the final location, the source explained.

Guandique was already in U.S. custody serving a 10-year sentence for attacking two other women when his arrest warrant for Levy's murder was issued last month.

After he arrives in D.C., Guandique will be charged with first-degree murder in Levy's 2001 slaying in the city's Rock Creek State Park, where he also attacked the other women.

Key to breaking the case were interviews — detailed in an affidavit supporting the arrest warrant — with at least two witnesses who claimed Guandique told them he killed Levy.

Click here for the arrest warrant and affidavit (FindLaw).

When detectives did zero in on Guandique, they visited him in prison in September 2008 and found a man with gang-related tattoos plus a magazine photo of Levy in his cell.

One witness interviewed last month told police that Guandique said over time that he and two male teenagers were sitting on a bench in a park smoking marijuana and cocaine when he saw Levy jogging.

The witness said Guandique thought Levy "looked good" and told the two teenagers that he was going to "get her."

Guandique said the three followed her along a path and at one point grabbed her and took her into the bushes, the witness said. When she started screaming, he allegedly grabbed her by the neck and choked her to death, so that people nearby would not hear the struggle.

The pending charges against Guandique come after an eight-year-long investigation that drew harsh criticism for D.C.'s Metro Police Department about botching the case in the days just after the California-born Levy was killed.

When her remains were found a year after she disappeared, they had decomposed so much that there was little forensic evidence investigators could collect.

Investigators spoke with Guandique in 2001 and 2002, and at one point gave him a polygraph test that was inconclusive.

They also questioned his family and friends, but found no leads relating to Levy. In a statement, his public defenders called the investigation flawed and said police had made numerous mistakes.

FOX News' Mike Levine and The Associated Press contributed to this report.