The Carter administration's search for a new director of the FBI now centers on federal Judge Frank M. Johnson Jr. of Alabama, Attorney General Griffin B. Bell's orginal choice to head the bureau, it was learned yesterday.

Johnson could not be reached for comment yesterday. His brother told a reporter in Alabama that he tought the judge "had gone to Florida on a fishing trip."

Bell is scheduled to announce the choice at 2:30 p.m. today.

The announcement will cap a scarch of more than six months for a successor for Clarence M. Ketley, who retires as FBI director at the end of the year.

It began, before Bell was sworn in as Attorney General, when Ben - a former federal judge himself - offered the FBI directorship to Johnson, who is a Republican. When Johnson turned it down, Carter appointed a nine-member committee to recommend candidates.

The committee, headed by Du Pont Co. Chairman irving S. Shapiro, reviewed 250 names and interviewed 50 individuals. It then recommended five men, including one FBI employee, Neil J. Welch, who heads the FBI's Pailadelphia office.

In presenting the recommendations to Carter, Shapiro mentioned several other possible candidates, including John A. Mintz, the FBI's chief counsel.

Mintz and the other five candidates were interviewed by Carter. One of the five, federal Judge Harlington A. Wood Jr., subsequently asked that his name be withdrawn from consideration.

Within the FBI, Mintz and Welch were considered the leading contenders. The FBI hierarchy tended to favor Mintz, while agents in the field lined up in support of Welch.

However, when Bell was asked in an Aug. 10 interview with the Chicago Sun-Times if the time being expended on finding a new director indicated the "right person" is not aamong the [WORD ILLEGIBLE] recommended by the search committee, he said, "Well, I guess that would be a fair assumption." Johnson was not among the five.

As in his previous statements, Bell, in the Aug. 10 interview, indicated he was not wedded to the idea of picking a director from either inside or outside the bureau.

Contrary to what most people think. I would prefer to find somebody in the bureau if I could. Most people say obviously you ought to get somebody from the outside, but there are still a lot of good people in the bureau.

But, I'm not bound to in or out; I'm just looking for somebody," he said.

Asked what qualities he was looking for in a FBI director, Bell said in the interview, "I'm looking for a leader, strong leader. I'm looking for somebody I think can manage. The third thing I'm looking for is somebody who knows either law or law enforcement. He doesn't necessarily have to be a lawyer or judge, maybe somebody who just knows law enforcement . . ."

Bell said he had tried to name Johnson as his deputy and Carter had asked him to head the FBI before Carter was inaugurated.

He is, as you know, an old friend of mine," Bell said. "I tried to get him to be deputy, and I really thought he was going to take the job, and he backed out on me, and I don't have any reason to think he would change his mind."

Bell described Johnson as a man who would meet all the qualifications he had in mind. "He never could bring himself to moving back into the outside world, which is a problem," Bell said. "He's been a judge a long time, and you wonder if you could adapt to normal society."

Johnson has been a controversial figure since he was appointed to the federal bench in 1955 by President Eisenhower following three years as an aggressive U.S. attorney.

He became immersed immediately in the civil rights court fights of the era and clashed early with a law school classmate, George C. wallace. That long-running confrontation escalated so much that in recent years many Alabama residents have come to regard Johnson, rather than Wallace, as the real governor of the state.

Johnson's rulings put the federal government in charge of schools, prisons, mental hospitals and even the election process.

His decisions over the years often were greeted with hostility. A cross was burned on his front lawn, a guard was placed around his home. In 1967, his mother's house was bombed.

The judge's first run-in with Wallace was in 1958 when Johnson cited the then-state judge with contempt of court for refusing to turn voting records for his county over to federal authorities.

Johnson later dropped the charge, saying Wallace had surrendered the records by means of "subterfuge." That statement became an issue in Wallace's 1962 race for governor, when Wallace denounced Johnson as "a scallawaggin', integratin', carpetbaggin' liar?" for suggesting he had cooperated with authorities.

Johnson and the Democratic governor continued to spar over the years, as the federal judge's decision took more and more power away from the state.

In 1975, for instance, Johnson ordered that Alabama prison officials couldn't accept any new prisoners until overcrowding had been alleviated.

He reasoned that sending a person to an Alabama prison at the time was "cruel and unusual punishment," forbidden by the Constitution.

Johnson's reputation as a proponent of civil rights reportedly cost him a seat on the U.S. Supreme Court during the early Nixon administration. At the time, Nixon was looking for a Southern Republican to take Abe Fortas' seat and was said to have decided on Johnson when a prominent Alabama GOP leader protested the appointment because Johnson was an integrationist.

Nixon turned instead to futile efforts to get two other Southern judges. Clemen F. Haynsworth Jr. and G. Harrold Carswell, confirmed.