(NewsNation) — Four Idaho college students were attacked as they slept nearly four weeks ago, but precious few facts about the case are known to the general public.

Former law enforcement officers, however, see telltale signs of a killer that knew their targets and their environment.

“This person has taken a huge risk,” said retired FBI agent Mary Ellen O’Toole said on NewsNation’s “CUOMO.” She believes the killer’s willingness to go into the home to commit this act means they knew a lot about the house and had likely been in it before.

Retired New York Police Department Sergeant Joseph Giacolone is also skeptical of the Moscow, Idaho Police Department’s decision to give the victims’ personal belongings back to their families.

“You’ve closed down the crime scene,” Giacolone said.

You can watch the full interview above.