Slidell attorney Alan Black, who finished third of four candidates in the race for district attorney for St. Tammany and Washington parishes, has thrown his support behind first-place finisher Brian Trainor.

Trainor faces Warren Montgomery in the Dec. 6 runoff. In the general election, Trainor finished first overall, with 38 percent of the more than 94,000 votes cast. Montgomery garnered 25 percent and Black earned 20 percent.

“While both candidates are good men, Brian is the most experienced candidate of the two remaining,” Black said in a statement about his endorsement.

Black’s nod could help Trainor further cement his hold on voters in Washington Parish, where he finished second to Black. Together, the two pulled in almost 70 percent of the Washington Parish vote.

Black also garnered the highest-profile celebrity endorsements in the race: television star Ian Somerhalder posted a message of support on his Instagram feed, and singer Stevie Wonder recorded a message of support for Black, whom he came to know while recording at a studio near Bogalusa where teenaged Alan Black worked.

Black said electing Trainor gives the best chance for some of his key ideas to be implemented: increasing specialty courts, including a court specifically for veterans; helping to address mental illness and addiction issues in the 22nd Judicial District; and allocating more resources to Washington Parish, by far the smaller of the two parishes in the district.

Trainor praised Black’s campaign and said the pair had talked “two or three times” since the election.

“Alan was a strong and honorable candidate in the race, and we’re honored to have his support,” he said. Black’s endorsement “broadens our base of support,” he added.

Roy Burns, who finished fourth in the race, has already endorsed Montgomery.

Follow Faimon A. Roberts III on Twitter @faimon.