Utah authorities have named a suspect in the unsolved disappearance of 19-year-old farmer Dylan Rounds, who was last heard from on May 28 when he told his grandmother he needed to get his grain truck out of the rain.

James Brenner, 58, is being held at the Weber County Jail on federal firearms charges, according to authorities.

Candice Cooley, Rounds’ mother, told Fox News Digital on Thursday that the newly named suspect is an "acquaintance" of her son.

"I’m keeping it together as best I can," she said.

Dylan Rounds poses in a flannel shirt

Dylan Rounds, a 19-year-old Idaho native who struck off on his own as a farmer in Utah, last spoke to family on May 28, according to authorities. (Box Elder County Sheriff's Department)

Brenner is described in court documents as a neighbor and "family friend" of Rounds who police say was squatting in a trailer on land where deputies found the missing teen’s boots and grain truck. His past criminal history includes malicious wounding, malicious shooting and three prior convictions for being a felon in possession of a firearm, court records show.

"The defendant has no work history and is currently unemployed and has no verifiable residence," court documents state. "The defendant was trespassing and squatting on property."

As part of their search for Rounds, investigators served several search warrants. Two of them led to federal cases against men who had interacted with Rounds before his disappearance – Brenner and Chase Venstra, 41.

Dylan Rounds with arms crossed in a hat and hoodie

Dylan Rounds, a 19-year-old Idaho native who struck off on his own as a farmer in Utah, last spoke to family on May 28, according to authorities. (Box Elder County Sheriff's Department)

According to a neighbor identified in court documents as DH, at some point after Rounds’ disappearance, Brenner asked him to conceal three black powder guns and a .22-caliber rifle without a serial number. After being contacted by the FBI, DH gave the weapons to authorities. Citing past felony convictions, they charged Brenner with being a felon in possession of a firearm.

Brenner pleaded guilty on May 21 and has already been sentenced to 33 months in prison for another firearm charge. The latest court documents were unsealed Wednesday.

"When Dylan Rounds was not located early on in the search effort, the investigation focused on the possibility of Dylan being the victim of a crime," Chief Deputy Cade Palmer, of the Box Elder County Sheriff’s Office, said Thursday. "The current totality of information gathered from the many interviews and searches, along with the analysis of both physical evidence and forensic data, has identified James Brenner as a suspect."

MISSING DYLAN ROUNDS: UTAH DEPUTIES SEEK PUBLIC'S HELP IN SEARCH FOR TEEN FARMER

Rounds bottle feeding pigs as a youngster

Candice Cooley says her son Dylan Rounds is singularly focused on farming. (Candice Cooley)

An Idaho native, Rounds struck off on his own as a teenager to build up his own farm in Utah, Cooley told Fox News Digital last month. He had a passion for the work and spent no time playing video games or on social media like others his age, she said, and he did not use drugs. 

She suspected foul play almost immediately when family members lost contact with him.

"No criminal charges have been filed specifically regarding the Dylan Rounds case," Palmer said. "This investigation is not complete and remains active. Law enforcement investigators are continuing to work to locate Dylan and find answers."

Dylan Rounds and Mom Candice Cooley pose outside log cabin

Dylan Rounds and his mom, Candice Cooley, in an undated photo. (Candice Cooley)

Venstra, the other man charged with a federal firearms offense, was remanded without bail by U.S. Magistrate Judge Brooke C. Wells.

UTAH TEENAGE FARMER MISSING MORE THAN 2 WEEKS AS MOM FEARS FOUL PLAY

Investigators said they found two guns in his motor home on May 12 – two weeks before Rounds’ disappearance, while serving a warrant in a homicide investigation. The weapons were identified in court documents as a Westernfield Model 550C shotgun with no serial number and a .22-caliber rifle.

Dylan Rounds driving a Tractor as a child

Dylan Rounds, 19, struck out on his own to become a Utah farmer, according to his mom Candice Cooley. (Candice Cooley)

After listening to Venstra’s jailhouse phone calls, detectives served another warrant on June 12 and allege that he asked an associate to retrieve and hide some of his belongings. They allegedly found a semiautomatic Stoeger 2000 shotgun, a Remington 700 rifle with an attached scope, and a Ruger 10-22.

The associate, identified in court documents as Witness A, also gave police a bulletproof vest and "multiple AR-15 style magazines," according to the affidavit. A further search of the home recovered yet another rifle, a Ruger M77 Hawkeye, allegedly concealed in a crawlspace. Authorities say Witness A told them that also belonged to Venstra.

Palmer had previously issued a blunt warning to anyone who may have been involved in Rounds’ disappearance.

"If somebody's laying low that was involved in this or knows something, and they think they lay low long enough we're just going to go away, that's not going to happen," he told Fox News Digital last month. "We're going to keep at this until we get answers."

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Rounds is a White male standing 5 feet, 10 inches tall and weighing around 160 pounds. He has brown hair and brown eyes.

Anyone with information on Rounds’ whereabouts is asked to call the Box Elder County Sheriff’s Office at 435-734-3800.

His parents are offering a $100,000 reward for his return.