A day before qualifying begins for the Nov. 4 election, the race to succeed Walter Reed as district attorney for the 22nd Judicial District suddenly became a four-way contest, with Covington lawyer Warren Montgomery saying he plans to run.

Three other candidates already have announced their intention to run: Slidell lawyer Alan Black, Covington lawyer Roy Burns and Brian Trainor, chief deputy for the St. Tammany Parish Sheriff’s Office.

Reed, who is under investigation by a federal grand jury, announced in July that he would not be seeking a sixth term as DA for St. Tammany and Washington parishes. He said he would not back any candidate to succeed him and urged his staff to remain neutral.

Montgomery, who said he decided to enter the race about a week ago, had not made any public announcement of his intentions. But civil rights organizer Belinda Parker Brown revealed his candidacy Tuesday at a news conference about the arrest of the district attorney’s brother, Richard Reed, on an allegation of sexual battery.

Brown decried Walter Reed’s administration as corrupt and said she is supporting Montgomery because she believes he is the only candidate who is not connected to what she called the “good ole boy” network.

Trainor spent eight years working under Reed as an assistant district attorney before moving to the Sheriff’s Office. Black did not work for Reed, but he frequently served as emcee at Reed’s fundraising events. During a closed-door meeting with his staff the day he announced he would not seek re-election, Reed described those two candidates as friends, according to a source.

Montgomery, 59, said he is running as an outsider, a mantle that Burns has been claiming for some time, issuing critical public statements with each fresh eruption in Reed’s ongoing political drama. Burns was an assistant district attorney under Reed’s predecessor, Marion Farmer.

Montgomery said he had been planning to qualify Wednesday without making a prior announcement. He decided to run, he said, because he was not satisfied with the current field of candidates. He predicted the campaign will cost him $500,000 and said he’ll be working hard to raise funds in the two-parish race.

“The politicos say that I’m late to the party, but I say that I’m crashing the party, and when the party is over, the good ole boys will be on the outside,” he said.

Montgomery has not yet filed a campaign finance report. According to the most recent reports, which came out earlier this month, Trainor had raised the most money, $111,989 in cash and in-kind contributions. Burns had raised the least, $17,000, but he had loaned his campaign $200,000. Black had raised $19,500 and loaned his campaign $25,000.

Concerned Citizens of St. Tammany, which is holding a candidate forum at 6 p.m. Aug. 26 at the John Davis Center in Lacombe, quickly added Montgomery to the lineup.

Follow Sara Pagones on Twitter, @spagonesadvocat.