NAVAJO, N.M. (November 3, 2009)—The FBI is investigating the death of a nun whose body was found in her residence at a church in a community on the Navajo Indian reservation near the Arizona-New Mexico border.

The FBI said Sister Marguerite Bartz, 64, failed to show up to Sunday Mass and a colleague who went to check on her discovered her body.

Investigators believe Bartz was killed between Halloween night and Sunday morning.

Authorities and officials with the Diocese of Gallup say they're not sure whether Bartz or the church were the target, or if the attack was random.

The diocese said Bartz entered the order in 1966 from Beaumont and professed final vows in 1974.

She ministered in Massachusetts, Louisiana and in several communities around New Mexico before ending up at the reservation church in 1999.