Idaho murders: Person in white car spotted on video has 'critical' information, police say

Police investigating the mysterious murders of four University of Idaho students say they're "confident" that the person or persons in a white Hyundai Elantra spotted near the crime scene has "information that is critical" to the case.

Authorities announced on Dec. 7 that they're looking to speak with the occupant or occupants of a white 2011-2013 Hyundai Elantra that was in the "immediate area" of the victims' house in Moscow in the early hours of Nov. 13, when the crimes occurred.

Police said they're investigating surveillance video from a Moscow gas station that shows the white car that morning.

"So far we have a list of approximately 22,000 registered white Hyundai Elantras that fit into our criteria that we're sorting through," Moscow police Capt. Roger Lanier said in a video statement on Thursday. "But it may not be all of them -- so the public can help us."

"Maybe one of your neighbors has one in the garage they don't drive that often. Maybe there's one that's just not on the registration database," he said. "Let us know."

Police have released this white Hyundai Elantra stock photo.

Moscow Police Chief James Fry said in a video statement Friday: "We have looked at massive amounts of video of footage, especially in the critical camera areas. We've looked at the 24 hours prior to and the 24 hours after ... and now we're extending that out even further to other cameras and other time frames."

"We have massive amounts of people looking at this -- multiple different groups just looking at the different videos at different locations, because we have investigators all across the nation that are reviewing these videos for us and sending us back information," the chief said.

The unsolved slayings took place in the early hours of Nov. 13, when roommates Kaylee Goncalves, Madison Mogen and Xana Kernodle, as well as Kernodle's boyfriend, Ethan Chapin, were all stabbed to death in the girls' off-campus house.

No suspects have been identified.

"This person went in very methodical," Kaylee Goncalves' mom, Kristi Goncalves, told ABC News on Wednesday. "I think he really thought it out. I think he was quick, I think it was quiet. And he got in and he got out."

Two roommates in the house survived. Police said the roommates are not suspects and likely slept through the murders. They were on the ground floor, while the four victims were on the second and third floors.

Lanier said Monday that police "do have a lot of information" in the case that they're choosing not to release to the public.

"We're not releasing specific details because we do not want to compromise this investigation," he said in a video statement.

Kaylee's dad, Steve Goncalves, urges anyone in Moscow with a surveillance system to come forward. He said he's worried some of those key videos could be erased now that a month has passed.

"You could save this case," he told ABC News.

But, Lanier added, "We understand that video has a finite life, and sometimes systems will record over itself, and so we started that process very, very early."

As students head home for the holidays, the chief promised that officers "will continue to keep up this pace" in the investigation.

Police urge anyone with information to upload digital media to fbi.gov/moscowidaho or contact the tip line at tipline@ci.moscow.id.us or 208-883-7180.

ABC News' Nicholas Cirone contributed to this report.