Eric and Dea Millerberg suspects of murder in Alexis Rasmussen case.

Eric and Dea Millerberg, the Utah neighbours of 16-year-old Alexis Rasmussen found dead after she mysteriously vanished six weeks ago while babysitting their child, are now “persons of interest” in the case.

Alexis Rasmussen from North Ogden vanished on September 10 after babysitting for neighbourhood couple Eric and Dea Millerberg, who are both currently behind bars on other charges.

On October 18, police found Alexis Rasmussen’s body in a shallow grave near Interstate 84 east of Ogden.

Weber County Attorney Dee Smith is now calling the couple “persons of interest” after Eric Millerberg, 36, was sent back to prison on Tuesday for violating his probation in a 2010 fraud case.

Dea Millerberg remains jailed after being charged on October 7 with two prescription fraud felonies.

Eric Millerberg was repeatedly in prison from 1997 to 2006 for burglary, discharge of a firearm and failure to stop at the command of police, according to Department of Corrections records.

Eric Millerberg was affiliated with Silent Aryan Warrios, a white supremacist prison gang group, The Salt Lake Tribune reported.

The man was originally convicted of forgery and credit card fraud when he was arrested for having drugs. Eric Millerberg did not reference the disappearance of Alexis Rasmussen during his court appearance.

Eric Millerberg claimed to have a prescription for oxycodone, which police found in his possession.

“I have pains. I have a metal plate in my neck and six screws,” he said.

Eric Millerberg was ordered to return to prison, where he is expected to serve up to a five year sentence.

Earlier this week Weber County Attorney Dee Smith said the public should not be fearing a killer at-large.

“I am confident police do know who is responsible for her death,” Smith told the Salt Lake Tribune.

“I don’t think (the suspects) are in a position where the general public needs to be worried about them.”

Authorities are waiting for the results of Alexis Rasmussen autopsy to decide on what the suspects will be charged with, and this could take at least a month, so the investigation will probably stretch into December.

“The body’s disposal suggests foul play, but I can’t say to what degree,” Smith told Salt Lake Tribune, adding investigators believe Alexis Rasmussen died soon after she disappeared and this is a “homicide”.

The Utah State Medical Examiner’s Office on Saturday confirmed through fingerprint and dental records that the body found at a rural site on Tuesday was that of Alexis Rasmussen.

Her family members had acknowledged that Alexis Rasmussen ran away before, and police previously said they were treating the investigation as a missing person case.

According to police, Alexis Rasmussen was last seen when she was babysitting on September 10, but she reportedly left before midnight to meet a friend. The boy claimed he only texted Alexis Rasmussen that night and did not meet her.