MOSCOW, Idaho – Investigators combing the Idaho city of Moscow and beyond for clues pertaining to the violent murders of four university students have so far come up empty in their search for information from local knife shops, Fox New Digital has learned.

Police investigating the mid-November stabbing deaths of four University of Idaho students have contacted local businesses seeking information about the fix-blade knife believed to have been used – but have so far had no success, Idaho State Police communications director Aaron Snell told Fox News Digital Wednesday morning. 

Investigators canvassed local businesses "early in the investigation" looking for information about a potential sale of a knife that matched the description of the murder weapon. 

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"There was no resolution to that," Snell said. "That was no real help to the investigation."

Snell would not comment when asked for a more specific description of the knife beyond what has been described and previously would not say whether any knives were taken from the home, or if police believed the killer brought the weapon to the crime scene. Investigators believe the suspect used a single blade to carry out the crime. 

Seventeen days since the victims were discovered, police have since towed five vehicles from the King Road home, and said they are in talks about when and how they will release the crime scene. 

On Wednesday, he said all of the vehicles that were towed from the home were previously searched and are "still part of the crime scene" and the ongoing search warrant. All five have been moved to the City of Moscow Maintenance Shop, where police can access them if the need arises. 

Snell would not say which electronic devices police had recovered from the home, and if any of the items or other property was found to have been missing. He said such information is "critical to our investigation."

The lifeless bodies of Madison Mogen, Kaylee Goncalves, both 21, and Ethan Chapin and Xana Kernodle, both 20, were discovered around noon on November 13. Officers responded around 11:58 a.m. to a report of an "unconscious person" at the address, and arrived to discover the slain students. 

Two victims’ bodies were located on the second floor, and two others’ were discovered on the third, police have said. 

The victims’ injuries indicated they were stabbed in their sleep sometime between 3 a.m. and 4 a.m., and some signs showed the victims trying to fight back, police said. 

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Two other roommates were on the bottom floor of the home at the time of the attack and survived, police said. 

Goncalves, Kernodle and Mogen were said to have lived in the home at the time. The residence was located just a block from the University of Idaho campus perimeter, and within eyeshot of some fraternity houses.

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A single marked police vehicle was seen parked outside the home on Wednesday. The perimeter remains lined by crime scene tape more than two weeks after the victims were found.

Officials have called the attack "targeted," despite some confusion as to how or why, and have not identified the intended victim.

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Police have said they have collected 113 pieces of "physical evidence" and captured about 4,000 photos of the crime scene. Investigators have received more than 488 "digital media submissions" via the FBI portal. 

Investigators are still working to identify a suspect, and have not yet recovered the weapon. 

Several vigils were held Wednesday across the state and in Washington State. The University of Idaho hosted a "vandal Family Candlelight Vigil" at the ASUI-Kibbie Activity Center beginning at 5 p.m. PT Wednesday.

The Moscow Police Department is urging the public to submit any images or information that they think could be important or useful to their investigation. They can do so by calling 208-883-7180, submitting tips through This email address is being protected from spambots. You need JavaScript enabled to view it., and sending digital media here. 

Authorities have also created a dedicated webpage related to the King Road attack.

Fox News Digital's Matteo Cina contributed to this report. 

Color may influence the way food tastes for picky eaters, according to a new study published in the journal Food Quality and Preference.

Picky eating usually "include[s] a limited diet, specific food preparation, strong dislikes and difficulty accepting new foods," the study noted.

Picky eaters will generally consume fewer than 20 different food items in their lifespan, according to a previous study — which can lead to nutritional deficiencies in iron, zinc, and fiber, plus health issues such as heart disease, dental problems and osteoporosis.

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"There is also a social cost because normally enjoyable moments between family members can easily turn into stressful, anxious and conflict-causing situations when picky eaters feel ashamed or pressured to eat food," said lead author Dr. Lorenzo Stafford.

The researcher studies the sense of smell in the department of psychology at the University of Portsmouth in the United Kingdom, according to a press release.

Stafford's research team did an experiment with some 50 participants to assess their food "neophobia, which is a reluctance to eat or try new food," the press release about the new study noted.

The smell and texture of food can affect how that food tastes for picky eaters — but research is limited in terms of how other senses influence taste for these types of eaters.

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So the researchers set out to find out how color influences taste in adult picky eaters.

The participants were mostly young adults with a mean age of around 20, but they ranged in age from 18 to 33 years old; 15 of them were male, 31 were female and one was non-binary.

The study divided the individuals into picky and non-picky eaters, based on their responses to a standardized measure called the Food Neophobia scale. 

Both groups then sampled the same snacks served in red, white and blue bowls.

The results showed the color of the bowls influenced how the picky group perceived the saltiness and desirability of the foods — but did not influence the non-picky group.

The picky group rated the snack served in the red bowel as least desirable and the snack higher in saltiness in the red and blue bowel — compared to the white bowl.

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"In the U.K., salty snacks are often sold in blue packaging, and the team believe that this might explain some of the saltiness findings," according to the press release. 

"Picky eating usually starts in childhood," Dr. Lama Bazzi, a psychiatrist in private practice in New York City, told Fox News Digital. 

"All kids are picky eaters … and the reason is it's about control," said Bazzi, who’s also an expert in trauma and eating disorders.

"As humans we want to be individuals, and we want to have control over our environment, so children get into the power struggle of being picky eaters — especially if their parents will engage," she added.

She explained that if picky eating is not addressed properly as a child, it can evolve later into certain eating disorders, such as ARFID, or avoidant restrictive food intake disorder.

"All of this comes down to a sense of control and a sense of safety," she told Fox News Digital.

So "when talking about the colors of the bowls [in the research study], it probably has to do with what makes that person feel safe, such as what colors are associated with safety," Bazzi said.

The colors blue, green and purple, she said, are considered "safer" colors — compared to the color red, which is usually associated with "stop." 

It makes sense, she said, "if you think of it from the point of view of control — and control being related to feeling safe in your environment — that eating food out of a bowl that's blue or colored in a color that feels safe, that you would want to eat more."

The concept is similar to the psychology of certain packaging grabbing people's attention in the supermarket.

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Sippy cups are colorful by design to entice kids, to give them a sense of safety and to make it fun for them to drink something, Bazzi noted.

On the other hand, bait for cockroaches or ants — or other items designed to stop the spread of something — are often in red-colored packaging. 

When advertisers want to entice consumers to buy chips or food, the packaging tends to use warm and inviting colors that remind people of their childhood, Bazzi added.

Stafford noted that the research is preliminary, yet the data may help picky eaters "expand the repertoire of foods," the release noted.

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"For example, if you wanted to encourage a picky eater to try more vegetables well known to be viewed as bitter, you could attempt to serve [these foods] on a plate or bowl that is known to increase sweetness," Stafford said in the press release. 

"Through further research, we could determine ways to help positively affect a person’s diet, and as a result their mental and physical health."