'Edged weapon' used in 'targeted attack' of four slain Idaho college students, police say

Federal officials are partnering with local police to investigate the murders of four college students in Moscow, Idaho, whose deaths were so gruesome that the local coroner said she is still processing what she saw, an FBI spokesperson confirmed Tuesday.

"They'll be looking under fingernails, they'll be doing all sorts of different exams," Latah County Coroner Cathy Mabbutt said. "It was all very, very traumatic."

FBI spokeswoman Sandra Barker declined to elaborate on what type of assistance is being provided. She said it is common for the bureau to offer investigative, technical and forensic assistance at the request of law enforcement agencies.

Police in Idaho said Tuesday they believe an "edged weapon," such as a knife, was used in the "targeted attack" on the four students, shedding light on a case that has left a shocked local community grappling with unanswered questions.

Police in Moscow said they have not recovered a weapon and came to the conclusion based on preliminary information. The victims — three women and a man, all students at the University of Idaho — were found dead before noon Sunday at a home about a half-block from campus, police said.

"Autopsies are scheduled to be completed later this week and will hopefully provide more definitive information on the exact cause of the deaths," police said.

All four deaths have been ruled homicides; police said they do not have a suspect in custody.

Mabbutt said the initial findings were “gruesome.”

“I’ve never seen anything like this in the 16 years I’ve been in this position,” she said, adding that she is hopeful the autopsies will be finished Wednesday.

"Investigators believe this was an isolated, targeted attack and there is no imminent threat to the community at large," police said, adding that they are re-creating a timeline of events to identify persons of interest.

Moscow Mayor Art Bettge has speculated the deaths might be linked to a property crime "gone wrong" or a "crime of passion," but without a suspect or without knowing whether anything was missing from the home, a motive remains elusive.

"Patience is needed to allow an investigation to proceed in meticulous fashion," he said.

The slain students were identified Monday as Ethan Chapin, 20; Madison Mogen, 21; Xana Kernodle, 20; and Kaylee Goncalves, 21.

In a memo to students, university President Scott Green said he and his wife were "heartbroken."

The school canceled classes Monday and was providing counseling and additional security for students and employees who said they didn't feel safe.

"Words cannot adequately describe the light these students brought to this world or ease the depth of suffering we feel at their passing under these tragic circumstances," Green said.

Moscow, a rural city of roughly 25,000 people just east of the Washington state line, "is, excepting recent events, quiet and crime-free," Bettge said. There hasn't been a homicide reported in the city in at least the past several years, according to police.

Chapin, of Mount Vernon, Washington, was a freshman and a member of the Sigma Chi fraternity majoring in recreation, sport and tourism management, the memo said.

Kernodle, of Post Falls, Idaho, was a junior and a member of the Pi Beta Phi sorority majoring in marketing.

Mogen, of Coeur d'Alene, Idaho, a senior majoring in marketing, was also a member of the Pi Beta Phi sorority.

And Goncalves, of Rathdrum, Idaho, was a senior and a member of the Alpha Phi sorority majoring in general studies.

"Pi Beta Phi’s current focus is on supporting our chapter members at the University of Idaho through this tragedy," the sorority said in a statement. "We ask that you respect the privacy of our members as they grieve."

The relationships among some of the students were not clear. In an Instagram post Saturday, Goncalves included an image of herself and several friends, including Mogen, and wrote: "One lucky girl to be surrounded by these ppl everyday."

In an Oct. 29 Instagram post, Kernodle wished Chapin a happy birthday and said life was "so much better with you in it."

This article was originally published on NBCNews.com