Rescue workers have located the body of Sen. Mark UdallMark Emery UdallSenate GOP rejects Trump’s call to go big on gun legislation Democratic primary could upend bid for Colorado seat Picking 2018 candidates pits McConnell vs. GOP groups MORE's (D-Colo.) brother, the senator's family announced late Wednesday.

James "Randy" Udall, 61, had been missing since last week. He had gone hiking alone in Wyoming.

"It is with great sadness that we announce the passing of our beloved Randy," Sen. Udall's family said in a statement. "Randy's body was discovered today by the heroic search and rescue team that worked for days to locate him in a remote area of the Wind River Range of Wyoming."

Search and rescue parties had begun combing the 225-square-mile Wind River Ridge mountains, where Randy Udall had gone missing. Udall's family thanked emergency officials for their efforts and said early indications suggested Udall died of natural causes.

"Our family is extremely grateful to Sublette County Sheriff Dave Lankford, his staff, Tip Top Search and Rescue, the United States Forest Service, Wyoming Air National Guard, and all others involved for their tireless efforts over the past several days," the statement said. "Although an autopsy is forthcoming, it appears he died of natural causes."

Randy Udall had been described by authorities as an "experienced hiker" but they suspected that he may have been suffering from a previous hip injury.

"Randy left this earth doing what he loved most: hiking in his most favorite mountain range in the world. He appeared to be on the obscure, off-trail route that he had proposed to his family," the family said in the statement.

"The entire Udall family is touched beyond words by the tremendous outpouring of support from people around the country. Randy's passing is a reminder to all of us to live every day to its fullest, just as he did."

"Thank you all for your prayers for my brother Randy," the senator tweeted late Wednesday.

Lawmakers were quick to express condolences. Rep. Kyrsten Sinema (D-Ariz.) tweeted, "horrible news," in response.

Similarly, Rep. Justin AmashJustin AmashTwo-year defense spending smooths the way to a ready military House Oversight a gavel no one wants Trump, GOP at new crossroads on deficit MORE (R-Mich.) tweeted, "please keep Sen @MarkUdall & family in thoughts & prayers. May his brother Randy's memory be eternal."