Jacob J. Spiegel, who was appointed Wednesday as special prosecutor in a probe of Sen. Edward W. Brooke (R-Mass.) by Suffolk County, Mass., is a 76-year-old former associate justice of the state Supreme Court who retired in 1972. He was incorrectly identified in yesterday's Washington Post as a result of misinformation supplied by a variety of Massachusetts sources.

Suffolk County District Attorney Garett Byrne yesterday appointed Jacob J. Spiegel, former chief justice of the state Supreme Judicial Court, special prosecutor for the probe into possible perjury charges against Sen. Edward W. Brooke (R-Mass.).

Spiegel, a 72-year-old Republican and 11-year veteran of the high court who retired two years ago, was chosen because "he has an extremely competent legal mind, he was eminently qualified and we felt the regular personnel here were too busy to handle it," said Byrne's aide, Kenneth Leary.

The announcement came shortly after Byrne, on a jurisdiction question, was handed the case by Middlesex County Probate Judge Lawrence T. Perera, who ruled June 15 that Brooke had testified falsely about his finances in a May 13, 1977, court deposition taken during bitter divorce proceedings between Brooke and his wife, Remigia.

Perera will hear motions today to set a date for a new divorce trial - an option he gave Mrs. Brooke because he said the senator's false testimony could have misled her about his finances - along with a motion by the senator appealing the decision to allow a new trial.

Brooke's false testimony - he has admitted making misstatements under oath - stems from his listing of a $49,000 loan he claimed came from a friend, liquor distributor A. Raymond Tye.

Under pressure from reporters and later in a preliminary court hearing on reopening the divorce trial, Brooke conceded Tye gave him only $2,000. The rest , he said, was money he was holding for his mother-in-law.

Mrs. Brooke has claimed the senator lied about the loan to boost his liabilities so he would pay her less in the divorce settlement.

In conceding that possibility, the judge stopped short of finding Brooke in contempt of court and referred the matter to Middlesex County District Attorney John J. Droney, Brooke's Democratic challenger in the 1972 Senate race.

Droney announced Monday, following a four-week investigation into possible perjury charges against Brooke, that the matter was beyond his jurisdiction because the false testimony was taken in the Boston offices of Monroe Inker, Mrs. Brooke's attorney at the time.

So, although the case was being tried in Middlesex County, the alleged perjury occurred in Suffolk County, Droney said, and would more appropriately be handled by Byrne.

Droney sent the case back with that recommendation to the judge, who referred it to Byrne with the same charge he initially gave to Droney: to take "such action as you deem appropriate."

Neither Byrne or Spiegel was available for comment yesterday.

Meanwhile, Brooke has stepped up his campaign for a third term in the face of the adverse reports.