Scott Illing, who came in third in the Oct. 24 primary for St. Tammany Parish sheriff, has thrown his support behind incumbent Jack Strain in the Nov. 21 runoff.

Illing, a retired U.S. Customs agent, was reticent immediately after the primary, saying he was not leaning toward making an endorsement of either Strain or Slidell Police Chief Randy Smith.

But Illing said Wednesday that he has had several meetings with the sheriff, whom he described as being “receptive” to the issues that had prompted his candidacy.

Illing described his concerns as the status of human relations in the Sheriff’s Office, budget efficiencies and ethics. He said the five-term sheriff was “receptive to correcting some of those things.”

“My vote will probably go to Sheriff Strain, and I am asking my immediate supporters to consider that,” he said.

Strain led in the primary, with 45 percent of the vote. But this is the first time in six races he has been forced into a runoff.

Smith captured 37 percent of the vote. Illing, whose support was mainly in western St. Tammany, received 13 percent.

Strain said he was honored to have Illing’s support and praised his campaign as one based on “passion and integrity.”

“He and his wife sacrificed their time and energy in an effort to keep St. Tammany a great place to live,’’ Strain said. “In the end, they recognized that the safety we enjoy is a result of an effective Sheriff’s Office and that the risk of changing it all could threaten the great progress we’ve made.”

Illing said he is not going to get too directly involved in the runoff campaign. His support is going to the incumbent, he said, because he is doing “an OK job” and has agreed to address his concerns. He also said that experience is on Strain’s side.

But Illing said he also thinks highly of Smith and wishes both contestants well.

James Hartman, spokesman for the Smith campaign, said he hopes Illing’s supporters will continue to vote for change and that some of his backers are hosting a fundraiser for Smith this week.

“It’s disappointing that someone who said he ran to take politics out of the Sheriff’s Office is now supporting the career politician instead of the career law enforcement professional, but it’s unlikely those who voted for Mr. Illing in the primary will follow his lead,’’ Hartman said.

Illing, who was a first-time candidate, said he has not ruled out a run for the office in four years, saying he will evaluate the situation at that time.

Follow Sara Pagones on Twitter, @spagonesadvocat.