Friends and family members of a Colorado man who went missing last month while rafting in the Arkansas River say he was searching for a treasure allegedly hidden by New Mexico author and antiquities dealer Forrest Fenn.

Eric Ashby, 31, had been rafting with three friends on June 28 when their raft flipped. While the three friends were able to make it out of the water safely, they told authorities they saw Ashby being swept away by the currents, the Fremont County Sheriff's Department in Colorado said in a statement.

The Sheriff's Department announced Friday that a body had been found in the Arkansas River. The department's Sgt. Megan Richards told ABC News that officers are still working to identify the remains and probably won't know for about a week if they are Ashby's.

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The news comes a little over a month after New Mexico Police recovered the body of Colorado pastor Paris Wallace, who went missing after telling his family members that he was searching for the gold and gems allegedly hidden by Fenn, and a year after authorities found the remains of Randy Bilyeu, who also went missing while searching for Fenn's treasure.

Fenn claims he hid a treasure -- estimated to be worth $2 million -- somewhere in the Rocky Mountains and included a poem with clues as to where to find the treasure in his self-published 2011 memoir, "The Thrill of the Chase." Part of the poem reads, "Begin it where warm waters halt / and take it in the canyon down / not far, but too far to walk / put in below the home of Brown."

Lisa Albritton, Ashby's sister, described her brother in a statement to ABC News as an "outdoorsman" and "a real adventurer." She said that he loved to solve riddles, "so when he heard about Forrest Fenn's treasure, of course, he was intrigued."

Albritton said her brother went to Colorado in April 2016 to search for the treasure. She said that now her parents are waiting on authorities to "identify the body that was discovered nearly a month after Eric went into the Arkansas River in Fremont County, Colorado," and that her family is hoping for "closure in these difficult times."

Dave Gambrell, one of Ashby's friends, told ABC News that Ashby "fully believed that he knew exactly where Forest Fenn's treasure was. He had me convinced, even peaked my curiosity."

Gambrell said he thinks Fenn should put an end to the treasure hunt that has already claimed the lives of two others.

"If I were to meet Forrest Fenn," Gambrell said, "I would say, 'What are you doing? Why are you setting people up for failure?'"

Fenn told ABC News in a statement that the treasure was not hidden in a dangerous place.

"It is terrible that Mr. Ashby is lost, but it is not likely that he was looking for the treasure. I have said many times that I was about 80 when I made two trips in one afternoon from my car to hide it. There was no reason for him to enter class 5 rapids in a small boat," Fenn added. "My heart and prayers go out to his sister and other members of his family."