Breckenridge police say Todd Barson turned himself in Friday following an incident at his home this week.
Investigators didn't release details, and a judge has issued a gag order in the case.
Barson has an unlisted phone number and couldn't be reached for comment.
Barson, fellow Democrat Bruce Brown and Republican Scott Turner were seeking to replace term-limited Fifth Judicial District Attorney Mark Hurlbert.
But Brown tells theSummit Daily News that Barson recently told him he planned to withdraw from the race.
Prosecutors in the 11th Judicial District are handling Barson's case to avoid any appearance of bias.