BATON ROUGE, La. (AP) _ A man taped by television cameras as he shot to death a martial arts teacher accused of kidnapping his son pleaded innocent and innocent by reason of insanity Thursday to charges of second-degree murder.

A trial date of March 19 was set for Leon Gary Plauche, 39, who remained free on $100,000.Plauche was indicted by a grand jury in November in the fatal shooting of Jeffrey Paul Doucet last March 16.

Doucet, 25, was being led handcuffed through Baton Rouge Metropolitan Airport by deputies who had been sent to California to bring him back on charges of kidnapping Plauche's son Jody, then 12. Television cameras taping Doucet's arrival showed Plauche turn from a pay telephone and fire a single shot into Doucet's right ear as he passed.

Plauche believed that Doucet had sexually molested the boy, said his attorney, A. Foster Sanders.

Since the shooting, Plauche has been in and out of hospitals for psychiatric treatment.

The dead man's brother, Roland Doucet, was present during the court proceedings, which were held under tight security. Spectators entering the courtroom were searched.

''I'd like to see him get the chair. But I know he can't,'' Doucet said in an interview before the arraignment.

Doucet said he was afraid public sentiment would be behind Plauche.

''I think it's going to be tried through the media, and it's going to be pro-Plauche,'' he said.

After the arraignment, Plauche was led from the courtroom through a rear door, accompanied by sheriff's deputies.

Sanders, in an impromptu news conference on the courthouse steps, said the judge had ordered attorneys not to discuss details of the case publicly.

Asked about Plauche's chances in a trial, Sanders said, ''I think a lot of facts have never been discussed and there will be a new perspective.''

If convicted of second-degree murder, Plauche would be given a mandatory sentence of life in prison without parole.

District Attorney Bryan Bush said he will ask for a sanity commission hearing to consider whether Plauche was legally insane at the time of the incident. The three-member independent panel would be appointed by the trial judge.