(MOSCOW, Idaho) -- The father of Kaylee Goncalves, one of the four University of Idaho students mysteriously stabbed to death in an off-campus house, said he's feeling "a little defeated" and frustrated by the lack of transparency from police.
But Steve Goncalves said he supports and trusts the law enforcement officers who are diligently working on the investigation.
"I have to assume and hope that this is all part of their plan and ... they've got this all figured out," he told ABC News. "I know that there's some really good, hard-working guys and girls that are on this case that I've met. And they looked me in the eyes and they told me straight-out that they're working and they're doing everything in their power."
Goncalves added, "My wife's biggest fear, part of the reason we didn't have a funeral, is because she couldn't be guaranteed that that monster was going to not be there."
Goncalves, 21, her lifelong best friend, Madison Mogen, 21, another roommate Xana Kernodle, 20, and Kernodle's boyfriend Ethan Chapin, 20, were killed in the girls' off-campus house in the early hours of Nov. 13. No suspects have been identified.
Two other roommates were in the house at the time and survived, appearing to have slept through the crimes, according to police. The surviving roommates are not considered suspects, police said.
"You can't imagine sending your girl to college and they come back ... in an urn," Goncalves said. "You're numb ... you can't absorb that amount of pain and agony."
Kaylee, the Goncalves' middle child, was planning to move to Texas. She had mentioned going to Chicago, but her parents said it wasn't safe enough.
"She was going places. She was highly motivated," her dad said. "I hope people understand how all these kids ... were doing everything right and they were going to be the type of people that you want to be your neighbor."
The Goncalves considered Mogen their "bonus child."
"When you're sick and you're down and you're out, you want to have that one great friend that's always there for you -- and that's what they had," Goncalves said. "There is no Kaylee without Maddie."
It's believed the four students were killed between 3 a.m. and 4 a.m. on Nov. 13, according to Moscow Mayor Art Bettge. On the morning of Nov. 13, the two surviving roommates called friends over because they thought one of the victims had passed out and wasn't waking up, police said.
At 11:58 a.m., a 911 call from one of the roommate's phones requested help for an unconscious person, police said. "Multiple people talked with the 911 dispatcher," police said, adding that they do not believe anyone at the house at the time of the 911 call was involved in the murders. Responding officers found the four victims on the second and third floors, police said.
Goncalves said the students died quickly and did not bleed for hours, so an earlier 911 call would not have saved their lives.
"Nobody suffered and nobody felt like that kind of pain," Goncalves said.
The murder weapon -- which police believe to be a fix-blade knife -- has not been found.
Goncalves said the victims suffered "large punctures" from a "brutal weapon."
"The detective said this weapon is probably something [the killer] paid money for and something that they're proud of," he said.
Goncalves said the only thing worse than losing his child is knowing that her killer is "having a great life out there -- and you're just left in shambles."
"I have to have my justice. These families deserve that," Goncalves said. "We just have to come together as a community. Submit all those pieces of evidence ... and get this guy off the streets."
Anyone with information can upload digital media to fbi.gov/moscowidaho or contact the tip line at email@example.com or 208-883-7180.
ABC News' Timmy Truong contributed to this report.