Howard Tanner went from champion debater at Miami Beach High to handling some of the thorniest criminal cases in New York, involving killers, hardened criminals and cops accused of corruption.

His most recent high-profile case involves defending a Brooklyn handyman caught on video spraying an elderly woman with gasoline, then tossing a firebomb at her in an elevator.

Taking on tough cases is something the prosecutor-turned-defense-attorney relishes. Tanner, 47, first honed his courtroom skills at Beach High, where he debated current affairs and such weighty issues as whether ketchup constituted a vegetable on school lunch menus.

Now, he takes on what is perhaps the most challenging case of his career, one with ties to his hometown: he is defending Narcy Novack, a former stripper accused of masterminding the murder of her millionaire husband, Ben Novack Jr., and his mother, Bernice Novack, whose husband built the fabled Fontainebleau hotel in Miami Beach.

Ben Novack Jr., 52, was found by his wife, bludgeoned to death with his eyes gouged out, in their hotel room in Rye Brook, N.Y. on July 12, 2009. The Fort Lauderdale couple was overseeing a business convention. His mother, 87, was found dead four months earlier in her Fort Lauderdale home. Her death, initially ruled an accident, was later deemed a homicide.

Jury selection starts Tuesday for the trial in federal court in White Plains, N.Y., where Narcy Novack, 55, and her brother, Cristobal Veliz, 58, are accused in a bizarre murder-for-hire scheme with plot twists rivaling a seamy pulp fiction novel. Prosecutors argue that the pair hired hit men in Miami to first eliminate Bernice Novack by beating her with a monkey wrench, then executing her son so that his widow would inherit the family’s estate.

NOT AN EASY CLIENT

Narcy Novack isn’t an easy client to defend. Before hiring Tanner, she voluntarily spoke with police detectives for a marathon 14 hours, detailing sordid details of her husband’s kinky sex fetishes and obsession with Batman memorabilia. She gave inconsistent answers and, at one point, tried to implicate a comic book collector in the murder.

Still without a lawyer, she agreed to take a lie detector test, which she all but flunked. She then let her husband’s body fester unclaimed in the Westchester County morgue for seven weeks before making funeral arrangements.

She surreptitiously emptied his safe deposit boxes by deceiving a Fort Lauderdale bank manager into believing that he was still alive.

Legal experts say Tanner, who has been practicing for 23 years, has his work cut out for him. But those who know him in and outside the courtroom say he is a master at discrediting witnesses, poking holes in police evidence and casting doubt in the eyes of skeptical jurors.

“He has people sense, common sense and street sense,” said James Leeper, Tanner’s former boss in the Brooklyn District Attorney’s Office where Tanner worked from 1989 to 1995.

Some say he will need to use everything in his arsenal to win acquittal for Novack, who prosecutors say was so determined to get rid of her husband and inherit his wealth that she watched the killers beat him to death and then ordered them to cut out his eyes.

At the time of his murder, police say Ben Novack, the owner of a successful convention planning business, was having an affair with a Miami tattoo artist and talking about leaving his wife.