KANSAS CITY, Mo. — Authorities on Monday said they are continuing to search for the bodies of two Wisconsin brothers who went missing in northwest Missouri during a business trip last week.

Clinton County Sheriff Larry Fish said investigators are still searching a 74-acre farm in Braymer for Nicholas and Justin Diemel, who went missing on July 21. Fish said the investigation turned from a missing persons investigation to a death investigation after law enforcement found the rental truck the brothers had been using.

A man who lives at the Braymer farm, 25-year-old Garland “Joey” Nelson, was arrested Friday after he told law enforcement he drove the brothers' vehicle to a commuter lot in Holt, Missouri, where he abandoned the truck. He was charged in Caldwell County with one count of tampering with a motor vehicle in the first degree.

On Monday, a judge denied bond for Nelson, who will have another bond hearing on Thursday in Caldwell County.

Fish said that Nelson has cooperated with law enforcement regarding the charge of tampering with a vehicle. Nelson has not been charged in the brothers’ deaths.

Nicholas and Justin Diemel rented a white Ford F-250 pickup truck after they arrived in the Kansas City area to check on cattle owned by their livestock company. The truck's GPS and surveillance video confirm the brothers drove the truck to Nelson's property from their hotel.

When the brothers didn’t return home as scheduled on Sunday, the Caldwell County Sheriff’s Office opened an investigation into their disappearance.

Nelson told authorities that he drove the truck from a residence in the 3300 block of Catawba Road to Clinton County, where he left it running with its lights on in the commuter lot, according to court documents.

Fish said Monday that the brothers and Nelson knew each other through a business deal that "had been going on for a few months."

Heavy rains in the area over the weekend have hampered the search for the two brothers, Fish said.

"That has definitely slowed us down," he said. "Trying to obtain any kind of evidence, you're at the mercy of nature."

Fish said authorities are considering the investigation to be "long-term" and said it will "take some time."