Human remains have been found in the search for two Wisconsin brothers who were last seen last week, Missouri authorities said Wednesday.

Nicholas Diemel, 35, and his 24-year-old brother Justin were visiting farms in Missouri's Clinton and Caldwell counties for their livestock business.

The human remains were found Tuesday at a farm in Braymer – about 70 miles northeast of Kansas City – where the Diemel brothers were last known to be, Clinton County Sheriff Larry Fish said.

Police said the farm is operated by Garland “Joey” Nelson, who is accused of tampering with a vehicle that authorities say was rented by the brothers.

Fish said forensic pathologists determined the remains found on Tuesday were human. He did not comment on the condition of the remains when they were found. Authorities said the human remains haven’t been positively identified and no cause of death has been determined.

Nick Diemel’s wife Lisa alerted authorities after the brothers missed their scheduled July 21 flight out of Kansas City, Fox 4 reported.

Investigators found the brothers' rental truck on July 22 in Holt, which is about 35 miles west of Braymer. Police said Nelson confessed to driving the brothers’ truck from the Braymer property to the lot in Holt and leaving it there.

Charging documents say Nelson abandoned the truck in a commuter parking lot near Holt after they visited the farm near Braymer. GPS data showed the truck arriving at the Braymer far and then leaving about two hours later.

YOUTUBE STAR GRANT THOMPSON FOUND DEAD ONE DAY AFTER HE WAS REPORTED MISSING ON A PARAGLIDING TRIP

Nelson is being held without bond at the Caldwell County Detention Center. Online court records do not name an attorney for him.

CLICK HERE TO GET THE FOX NEWS APP

In 2016, Nelson was sentenced to two years in prison for selling more than 600 head of cattle that did not belong to him. Federal prosecutors said at the time that Nelson pleaded guilty to cattle fraud that caused more than $262,000 in losses. He was released from prison in March 2018.

He also pleaded guilty in August 2015 to two misdemeanor counts of passing bad checks.

Fox News' Robert Gearty and The Associated Press contributed to this report.