Authorities are working to determine whether a human skull found in Panama is that of a missing American woman who disappeared almost two years ago, the FBI told FoxNews.com.
Yvonne Baldelli, of southern California, was last seen in November 2011 in Isla Carenero, one of several islands in the province of Bocas del Toro on Panama's Caribbean coast. In June, U.S. authorities arrested Brian Brimager, a retired Marine and Baldelli's former boyfriend, on charges of obstructing justice in connection with the 42-year-old woman's disappearance.
Prosecutors claim Brimager, of Dana Point, Calif., assaulted Baldelli, also of Dana Point, multiple times shortly after the couple arrived in Panama in October 2011. The unsealed indictment alleges Brimager began emailing another woman, the mother of his young daughter, about plans to move back to California and help raise their child. The emails did not mention Baldelli, according to prosecutors.
On Tuesday, a Panamanian resident who lives on Isla Carenero found a "green military style" backpack containing a human skull and some bones, but not a complete skeleton. The bag also contained women's clothing, according to law enforcement.
Police there told a Panamanian website that the size and shape of the skull indicated the victim most likely was female.
Baldelli was living with Brimager at the time of her disappearance. Some 10 days after last being seen with Baldelli, Brimager left the country for Costa Rica and then the U.S., where he is now married and living in California.
Baldelli was reported missing by her family in January 2012 after she failed to show up for a family reunion.
U.S. prosecutors say that, after killing Baldelli, Brimager traveled to Costa Rica as part of an elaborate ruse to have it appear she left Panama for another man. Brimager used Baldelli's ATM card in Costa Rica after her disappearance to make it look as though she was still alive, according to prosecutors, who claim Brimager also conducted an Internet search on Baldelli's laptop with the words: "washing mattress blood stain."
Brimager has denied any involvement in Baldelli's disappearance.
Cristina Corbin is a Fox News reporter based in New York. Follow her on Twitter @CristinaCorbin.