Presidential adviser Charles Kirbo says he is conducting a personal investigation syndicated columnist Jack Anderson and has been turning over his findings to the FBI.

"I've got a good case against him," Kirbo said in an interview published yesterday by the Atlanta Journal-Constitution. "I have yet to decide what to do with it."

Anderson said the investigation was an attempt to discredit him. In recent columns, he has outlined an alleged scheme to pressure the Carter administration into easing legal pressure on fugitive Robert Vesco, who fled the United States after being accused of illegally taking millions of dollars from an international investment company.

According to Anderson, the scheme was aimed at several people close to Carter, including Kirbo.

Anderson said the administration halted any serious effort to extradite Vesco after the scheme was put into motion. But he stopped short of saying that Vesco's plan was responsible for the change in policy. Later, Anderson published a column in which he said he had discovered that some of the documents used in preparing his earlier columns had been "reconstructed" by his sources. The documents had implicated Kirbo and Carter aide Hamilton Jordan in the Vesco affair.

Andersonn said his investigative work led to the discovery, but in the Journal-Constitution interview, Kirbo said he had proof that Anderson learned of the reconstruction from a woman who contacted one of Anderson's investigators.

"He's just trying to dig out from the damn thing now," Kirbo said.