A University of Florida researcher studying the criminal mind has been conducting experiments on the brains of prisoners executed in Florida without the prior permission of the Death Row prisoners or their families, according to officials in the Florida medical examiner's office.

The number of men whose brains have been examined was uncertain yesterday. One civil rights lawyer looking into the case put the number at 11, but officials were unable to confirm that figure. Lori Naslund, an investigator in the medical examiner's office, said that neither the prisoners, before their execution, nor their families had given permission for such experimentation.

The research is designed to determine whether head trauma during childhood is related to "aberrations of behavior, particularly aggressive behavior," Dr. William Hamilton, a state medical examiner, said in a prepared statement issued in response to inquiries from The Washington Post.

The researcher approached Hamilton several years ago and asked him for the brains of electrocuted state prisoners, according to Naslund. The researcher, identified by Naslund as Christiana Leonard, could not be reached for comment. But Henry Schwarzschild, an American Civil Liberties Union lawyer, said yesterday he had spoken to Leonard and that she confirmed that experiments had been conducted on the brains of men she understood to be executed Death Row inmates.

Hamilton, in the prepared statement, justified the experiments legally by citing a state law which he said allows organ research "related to the cause of death," without permission. In the cases of executed men, he said, one of the causes of death usually was violent behavior, since it led to the crimes for which they were executed. Thus, in studying the violent behavior, he suggested, scientists are studying factors "related to the cause of death."

"In the case of executed prisoners, violent behavior usually led to the acts for which the death sentence was imposed . . . ergo observation of the microscopic structure of the amygdala the part of the brain being studied is distantly related to the cause of death," Hamilton said.

The experiments have been the subject of investigation by the ACLU, among others. Schwarzschild said that he has spoken with Leonard, and that she did confirm the experiments. He said it was his understanding that the study concerned the relationship between trauma -- "battered child syndrome trauma" -- and future behavior, including criminal behavior.

"She Leonard said she thought the findings that might ultimately come out of the research might be helpful to us as opponents of the death penalty because it might throw some light on the origins of criminal conduct," he said. This could provide a further basis for arguing that certain individuals accused of capital crimes were incapable of understanding or controlling their behavior.

Schwarzschild said, however, that he has not confirmed that the brains in question came from the bodies of the executed men. He said he failed to understand the circumstances under which they might have been obtained by the researcher.

If such experiments have taken place, he said he was "outraged humanly on behalf of the people who are executed, and on behalf of their families, who have suffered enormous pain . . . . I am outraged at the state doing this when there is clearly no medical or legal reason for it and when there is very serious legal doubt whether this is required or authorized."

Susan Cary, a Florida public defender who handles capital cases, said she has handled funeral arrangements for all executed inmates and had helped their families make funeral arrangements. To her knowledge, she said none had been approached about experiments. She said Florida law required authorization from family or subject for any organ donation or experimentation.

The families of the electrocuted prisoners have not been told that a researcher conducted such experiments, according to Joseph Ingel, director of the Southern Coalition on Jails, in Nashville. "We want to break it to them Monday or Tuesday," Ingel said. Ingel said that according to his information, the number of men involved was 11. Thirteen men have been executed in Florida since the mid-1970s.

Civil rights lawyers have asked Leonard to stop her experiments or seek permission from prisoners on Death Row but she has not committed herself, according to Ingel. The lawyers intend next week to tell the six prisoners who are scheduled to be executed next about the experiments to give them the opportunity to grant or deny permission, Ingel said.

The warden of the Florida state prison in Starke, Fla., Richard Dugger, said he did not know that a researcher was conducting experiments on the brains of electrocuted prisoners. "The medical examiner takes the bodies and we don't have anything more to do with them," Dugger said.