A Catholic church spokesman says an arrest in connection with the slaying of a nun on the Navajo reservation should help people sleep better. But federal authorities remain tightlipped on its significance.

The FBI said agents arrested one person in the reservation community of Navajo after Thursday as part of their probe into the killing of 64-year-old Sister Marguerite Bartz. Her body was discovered after she didn't show up for Sunday Mass.

News of an arrest resulted in some relief for the community in northwestern New Mexico, said Lee Lamb, a spokesman for the Diocese of Gallup, which oversees the St. Berard parish in Navajo where Bartz lived.

"I'm sure that community hasn't been sleeping well for many nights. I think with this arrest they're going to have a better night's sleep tonight and feel a little safer in their homes," Lamb said.

Lamb said with the arrest, the community as well as the Sisters of the Blessed Sacrament — the order to which Bartz belonged — can focus on the nun's funeral, the grieving process and the celebration of her life.

Parishioners said Bartz served Navajo and the surrounding communities for a decade and had success converting people through her work.

FBI spokesman Darrin Jones would not say why federal investigators were not releasing any information about the arrest, and Samson Cowboy, the head of the Navajo Nation's public safety department, also declined to comment, saying only: "It's a very sensitive issue."

The FBI did confirm that the person arrested Thursday morning would remain in custody for the night.

Investigators also remained tightlipped about details of the crime, but said preliminary autopsy results show Bartz sustained substantial trauma, likely as a result of a violent confrontation with her killer or killers.

Jones said agents were withholding the specific cause of death while the investigation continues. However, he said there was no evidence to suggest Bartz was sexually assaulted or that she was targeted because she was a nun or for religious reasons.

Diocese officials said the community has questions about whether the crime could have been the result of a robbery, if it was gang-related or possibly connected to a break-in at the parish last month.

FBI investigators have combed Bartz's home for evidence and a mini-SUV she had used was transported to Albuquerque for processing by investigators. It arrived Wednesday with a sheet draped over the driver's side, covering the window. The FBI has said Bartz's murder apparently happened Halloween night or early Sunday.

When parishioners talked about Bartz on Wednesday, they spoke of her in the present tense.

"She makes me and my family feel really safe," Arlene Deche said.

Deche and others said Bartz prayed with them in their homes and traveled to the homes of elders on the remote reservation. She offered advice on raising children, ran bingo and religious education classes, played guitar and learned the Navajo language to sing Navajo songs.