Volunteers led by his ex-wife eventually picked up where the official search left off, and his remains were found several months later.
Mr Wallace's wife Mitzi reported her husband missing on 14 June and following an extensive search of the pastor's belongings in his hotel room, and the trails and woodland in the Espanola area, his vehicle was eventually found along the river.
The buried treasure was referenced in Fenn's poem that was contained in Fenn's book, The Thrill of the Chase.
Rescuers spent two days searching the river and found a body Sunday that investigators believe to be Wallace's. New Mexico's top law enforcement officer is asking Fenn, the author and antiquities dealer who inspired thousands to comb remote corners of the West in vain for a chest of gold and jewels to end the treasure hunt.
As the Sentinel's Erin McIntyre reported, Fenn has warned treasure hunters repeatedly to stay away from unsafe terrain.
Randy Bilyeu moved to Colorado from Atlanta in 2014 to hunt for the treasure. His wife reported him missing after he missed a meeting last Wednesday, and his belongings were later found at a hotel in Espanola, New Mexico.
Two Colorado men have already died in the search, other treasure hunters have had to be rescued.
Wallace's is the second person believed to have died searching for Fenn's treasure. "People are coming from other states and other parts of the world to find this elusive treasure that may or may not exist with very few clues and they are underestimating New Mexico", he told KRQE News 13.
"He's putting lives at risk", said Mr Kassetas. "He lost his life for a hoax", she told the Albuquerque Journal previous year.
Image: Author Forrest Fenn is contemplating calling off his treasure hunt challenge.
New Mexico's search and rescue team launched a survey Tuesday on whether Fenn should call off the search. "I have said, don't search any place where a 79 or 80 year old man couldn't hide that treasure chest", he said. "We're disappointed that he lost his life because of a treasure hunt".
"Please don't over extend yourself", he said. "I was 80 or about when I hid the treasure and it was not a hard task. I wanted a man and his wife and their three or five kids to get off the couch and out of the game room and go look for it", he told the Nightly News in 2013.