Adam Eugene Cox, 33, pleaded guilty Tuesday to threatening to kill Maricopa County Sheriff Joe Arpaio and his family.

Cox was originally arrested on January 27 as the main suspect in an Arpaio death threat investigation that began on the Internet.

Cox's threats read, in part: "I plan to kill Arpaio first. He will be filled with a thousand bullet holes before the year is out. I promise you this. He won't f**k with Obama. He will be buried 10 feet under and his whole family will be murdered along with him."

Cox's postings indicated that he is an avid President Obama supporter, and that Apraio's investigation into the legitimacy of Obama's birth certificate may be behind his threat to kill the sheriff. Cox's mother confirmed with police that he is an avid President Obama supporter.

Deputies in Knoxville, Tennessee worked with Maricopa County Sheriff's deputies to serve a search warrant and seize a computer and other evidence from the home of Cox.

"Every threat will be taken seriously, and the sheriff knows that his position often attracts threats but he draws the line when his family is threatened," said Deputy Chief David Trombi, whose detectives have overseen the threat investigations against Arpaio.