A Utah family was mysteriously found dead inside a bedroom at their home over the weekend. They were neither shot nor stabbed, but the causes of deaths of the Utah family could remain a mystery for weeks to come, said the Springville Department of Public Safety on Monday.

Police are still investigating after five members of the Utah family were found dead Saturday around 8 p.m. They were discovered by an older son in the parents' bedroom.

The son, about 18, reportedly made the discovery as he went to the duplex after he did not hear from the family as expected. His name was not released, reports the Associated Press.

The Utah family found dead was gathered in the room at the home in Springville, near Provo, about 45 miles south of Salt Lake City, said Springville Police Lt. Dave Caron.

"They had talked to them earlier [Saturday], the family been in touch but nobody had heard from them, so they stopped by and that's when they found them," said Caron.

The family members later identified as 37-year-old Benjamin Strack, his 36-year-old wife Kristi Strack, and their three children, 14-year-old Benson Strack, 12-year-old Emery Strack and 11-year-old Zion.

According to a preliminary autopsy, the Utah family found dead didn't die from a violent assault.

Firefighters also tested for carbon monoxide and entered the home wearing special equipment. However, they found no traces of the odorless poisonous, gas, said Caron.

Finding no trace of the gas still does not rule out carbon monoxide, Caron added. He said the open doors could have brought in wind and rain from a storm, which is capable of clearing the gas in the room with the Utah family found dead.

"We looked into the possibility it could have been carbon monoxide but we just don't know at this point," said Caron.

He also said that the family's three pets - a kitten, a full grown cat and a ferret -all survived.

The animals' survival does not confirm if there had been poisonous gas in the house at one point, reports CNN.

There were also no notes or other evidence found by police to indicate what killed the Utah family found dead, Caron said.

"I really don't like an unsolved mystery ... those kind of things grate on you," he said.

Meanwhile, the Springville DPS said the medical examiner has indicated that the next move would be to continue the investigation through the blood sample analysis. This could determine what killed the Utah family found dead, said the DPS.

Though the blood samples from all five of the Utah family found dead are being analyzed by the examiners, the process could take weeks, sometimes months, to finish.

"Before you can get all of the results, all of the chemical tests, the blood work and that stuff at the results from the lab back," said Caron.

Meanwhile, police said they also intend to analyze beverages and food which the Utah family could have consumed.

As for ruling out foul play, Caron said they are not ruling out anything.

"We haven't ruled out anything except there was no violent trauma. We're going to look at everything," said the lieutenant.

On Sunday, according to Fox 13 Now, a press release has been issued by the department.

"Preliminary autopsy results for the family of five who were found dead in their home have ruled out any sort of violent assault...The Medical Examiner has indicated that the next step is to continue the investigation through analysis of blood samples to determine what may have caused the deaths," said the release.

A friend by the name of Jim Phillips, a friend who also acted as a spokesman for the Utah family found dead said the Strack family wasn't ready to comment.

"The family is obviously grieving their loss," said Phillips. "They're coming together and have asked for understanding and patience," he added.

Benjamin Strack had been working off-and-on for six to seven years at AK Masonry, a bricklaying company. Company owner Alex Short said he had borrowed money in the past.

"He borrowed some money to pay rent," Short said. "That money still hasn't been repaid."

Strack was a good employee when on the job, said the owner. However, he would often be absent for days at a stretch.

"We hadn't seen him for the last two weeks," said Short.

According to court records, in 2008, Benjamin and Kristi Strack pleaded guilty to misdemeanor forgery charges. In the following year, they also pleaded disorderly conduct.

The family's financial history and other personal details aren't part of the police's investigation as of the current moment. However, they said the scope could widen if they find foul play involved in the demise of the Utah family found dead.

On Friday, neighbors spoke to Fox 13 about the incident.

"It was especially sad to hear that it was the whole family," said neighbor Ame Patton.

The area where the duplex was located was described by neighbours as a pretty social neighbourhood, where everyone knows anyone. However, they added that the Utah family found dead had opted to keep to themselves.

Neighbour Reilly Strecker, who lives in the other half of the duplex, told the Deseret News that the children were homeschooled.

The Utah family found dead was kind, but Strecker also pointed out that they kept to themselves. Their children were also shy, Strecker told the paper.