The former Arizona sheriff now faces up to six months in prison for refusing to comply with a 2011 U.S. court order that prohibited him from targeting people he suspected of illegally immigrating to the United States in traffic patrols, the Associated Press reported.
U.S. District Judge Susan Bolton, who found Arpaio guilty of misdemeanor contempt of court, wrote that Arpaio had "announced to the world and to his subordinates that he was going to continue business as usual no matter who said otherwise."
Arpaio was an early supporter of Trump, endorsing him during a Jan. 26, 2016 campaign rally months before he won the Republican nomination.
“It’s easy to endorse him,” Arpaio told the crowd of supporters gathered in Marshalltown, Iowa. “Everything I believe in, he’s doing and he’s going to do it when he becomes president.”
Trump would tout Arpaio’s endorsement at several campaign rallies during the election to back his claim that he was “tough on borders.”
“When Sheriff Joe gives you an endorsement, you know you’re the king of the border, right?” Trump said at a campaign rally on Feb. 2, 2016.
“[Arpaio] is the best. So he endorsed Donald Trump and that means that my plan is the best, my plan is the strongest,” Trump said at another rally a few weeks later in Oklahoma City.
Arpaio also took the stage to speak about Trump at the Republican National Convention last year.
While Trump won the presidency partly by promising to crack down on illegal immigration and build a wall along the U.S.-Mexico border, Arpaio lost his bid for re-election in 2016.
Following the election, Arpaio was even being considered to join the Trump administration as the head of the Department of Homeland Security, according to Washington Post and Washington Times reports at the time.
Arpaio is set to be sentenced on October 5. His attorneys have said they will appeal.
On Twitter, a number of Trump supporters have been calling on the president to support a “patriot” and pardon Arpaio, which is constitutionally possible.
The constitution states that the president “shall have power to grant reprieves and pardons for offenses against the United States, except in cases of impeachment.”
The White House did not immediately respond to ABC News’ request for comment.
The Associated Press contributed to this report.