Frank Norris, in his Naturalistic novel McTeague, does not give details to McTeague's actual death. Instead, he lets readers assume that he simply dies of exposure and being "locked to the body."
Norris does not offer the details to McTeague's death because the circumstances surrounding his death are not important (unlike the deaths of Trina and Maria, which are described in great detail).
Norris was a Naturalistic writer. Therefore, he believed in the power of nature and its superiority over mankind. For Norris, nature was the "one" who controlled all else. Man simply had no control over his life. Therefore, the lack of descriptive details surrounding McTeague's death was a conscious one. Norris simply left his death to nature.
The fact that McTeague was both tied to a dead man he hated (the world of mankind) and a dying bird he loved (the world of nature) showed the inevitable power of nature.