MOSCOW, Idaho -- It's been more than one month since the killing of four University of Idaho students, and the murderer is still on the loose.
Investigators said they are now widening their search area as they look for more video evidence.
This, as students begin returning home for the holidays.
Investigators are zeroing in on that grainy surveillance video of a white car at a gas station the morning of the murders. They are looking through the registration of thousands of cars that match the description, and are asking the public for help finding clues.
As the University of Idaho empties out for winter break, the families of the four students brutally stabbed to death last month are growing increasingly concerned that critical evidence in the search for the murderer could be disappearing.
"I asked the community if, you know, you have a tape, if you know that there's a recycle time and it's getting close to that, take the extra step. Go in there, look for it, pull it off," said Kaylee Goncalves' father, Steven Goncalves.
The parents of Goncalves are pleading for anyone with possible surveillance video to come forward.
This, as police reveal they are combing through 22,000 cars that match the search criteria of the one they're looking for a 2011 to 2013 white Hyundai Elantra.
That car resembling the one in a grainy image captured on a gas station security camera that was taken around 3:45 a.m. the morning of the murders.
Police believe the occupants of that car could have information critical to the investigation.
"This white car plays into two possibilities. One, it's the bad guy's car. Obviously, you want to find that. Secondary, they might be witnesses to something," said ABC News contributor and former FBI agent, Brad Garrett.
Investigators also said they are now widening the search area as they continue to look at video evidence.
"We've looked at the 24 hours prior to and the 24 hours after of those and now we're extending that out even further to other cameras and other time frames," said Moscow Police Chief James Fry.
The Goncalves are also searching for clues.
"Who can do something like this," Steve asked.
"Where are you? Who are you," Kristi added.
They have questions about the behavior of Kaylee's dog that was found in the home, but police have said "there was no indication the animal had entered the crime scene."
"If he was locked in a room, I would guess that he would bark and claw and whine," Kristi said.
As for the two of the roommates surviving who were unscathed, Kristi empathizing with them.
"They're victims, as well. And I'm sure they're terrified," she said.
In the meantime, the university is beefing up security on campus. The provost said they expect some students won't return to campus after winter break.
"A lot of people said they wanted to go home and be with family, and we support that," said University of Idaho provost Torrey Lawrence.
With the holidays approaching, police are vowing to keep up the pace of the investigation. They said they have investigators assisting from all across the country.
This, as the devastated parents continue to demand more answers.