Secretly recorded FBI tapes will show that a Ku Klux Klansman who was angered by civil rights demonstrations took part in the 1963 church bombing that killed four black girls, a prosecutor told jurors Tuesday.

U.S. Attorney Doug Jones said defendant Thomas Blanton Jr. plotted the bombing with other Klansmen and later giggled about the girls' deaths.

Blanton, 62, is charged with murder in the Sept. 15, 1963, bombing at the Sixteenth Street Baptist Church, a downtown gathering place for civil rights protesters. The dynamite blast on a Sunday morning killed 11-year-old Denise McNair and 14-year-olds Addie Mae Collins, Cynthia Wesley and Carole Robertson.

Jones, prosecuting the state murder case under a special arrangement, said FBI tapes made with a microphone hidden in Blanton's kitchen will show his wife asked him about a meeting he had with other Klansmen at the Cahaba River bridge.

At one point, Jones said, Blanton responded with giggles.

"He giggled about going to the river to plan a bomb that killed Denise, Addie, Carole and Cynthia," said Jones.

In 1963, Birmingham was the site of demonstrations against separate lunch counters and water fountains as efforts began to desegregate schools, and many white people didn't like the demonstrations, the prosecutor said.

"Thomas Blanton was one of those people, and I submit he couldn't stand it," Jones said.

He also said a man who was keeping watch outside the church will identify Blanton and Robert "Dynamite Bob" Chambliss as being near the front steps on a night about two weeks before the bombing. Chambliss was convicted of murder in the bombing in 1977 and died in prison.

Several members of the victims' families sat on the front row of the courtroom's spectators' section.

The opening statements were given after Circuit Judge James Garrett, without elaborating, rejected defense motions for a mistrial and a change of venue.

The mistrial motion by defense attorney John Robbins was based partly on news reports last week by The Associated Press and ABC news on tapes of Blanton secretly recorded in the 1960s by FBI informant Mitchell Burns. Those tapes came from a recorder the FBI had hidden in the trunk of Burns' car.

The change of venue motion alleged excessive publicity about the case in Birmingham.

The jury includes eight white women, two white men, three black women and three black men. Which of the 16 will be alternates will not be known until deliberations begin.

Blanton has pleaded innocent and has said repeatedly over the years that he was not involved in the bombing. Prosecutors contend it was carried out by a handful of Klansmen to intimidate blacks seeking an end to segregation laws.

Jurors will be sequestered throughout the trial, which could last two weeks or more.

Another former Klansman, 71-year-old Bobby Frank Cherry, was indicted along with Blanton but his trial was delayed by questions over his mental competence. A fourth suspect died without being charged.