LOS ANGELES, Sept. 1 – Former Charles Manson follower Leslie Van Houten will be tried for the third time for the Aug. 10, 1969, slaying of Leno and Rosemary LaBianca, Dist. Atty. John Van de Kamp said today.

Van de Kamp’s decision shattered the former Monrovia High School homecoming princess’ hopes for avoiding another trial via a plea bargain.

Before reading a one-page statement at a press conference in the downtown Criminal Courts Building, Van de Kamp told reporters he would have no further comment so as to “not fuel the fire” of publicity that has surrounded the case.

In the prepared statement, Van de Kamp said: “The decision to retry the case was made after the prosecution carefully considered whether the evidence involved supports a finding of a deliberate and premeditated murder with malice aforethought, and whether the jury can reasonably conclude from the evidence that the defendant lacked the mental capacity to commit the offense.”

Miss Van Houten’s second trial cost taxpayers $284,274, according to County Supervisor Kenneth Hahn. The first trial, which included Manson and three women followers, cost $768,838 bringing the total cost of trials in which Miss Van Houten was involved to $1,053,112.

Van de Kamp announced that Dep. Dist. Atty. Stephen Kay will again handle the prosecution’s case, and will be assisted by Dino Fulgoni, a veteran prosecutor who is a specialist in psychiatric matters.

It is expected that Los Angeles lawyer Maxwell Keith will continue to represent Miss Van Houten. He was not immediately available for comment. Had a plea bargain for second-degree murder been reached, there would have been a strong likelihood of Miss Van Houten’s being freed in the near future. The eight years she has been behind bars is longer than the average second-degree murder term.

Her second trial ended Aug. 6 when the jury reported on its 25th day of deliberation that it was “hopelessly” deadlocked.

Kay had sought a first-degree murder verdict, saying that Miss Van Houten had admitted in her testimony that she decided she wanted to go along the night the LaBiancas were slain even before Manson asked her.

Keith did not ask the jurors to find her not guilty but told the jurors they should return a verdict of manslaughter.

Five psychiatrists called by Keith testified that Miss Van Houten could not “meaningfully” premeditate the killing of a human being.

Kay countered with the testimony of San Francisco psychiatrist Dr. Joel Fort, who offered a lengthy rebuttal to the defense doctors.

Miss Van Houten, now 27, was convicted of first-degree murder in the first trial along with Manson and fellow “family” members Susan Atkins and Patricia Krenwinkel.

The State Court of Appeal overturned Miss Van Houten’s 1971 conviction last fall on grounds that she should have had her case severed from the other defendants when her attorney, Ronald Hughes, disappeared during the trial.

By BILL FARR