A leading medical school in California apologized for unethical experiments members of its faculty conducted on local prisoners in the 1960s and 70s.

The University of California, San Francisco issued a statement Thursday apologizing for experiments two members of its faculty conducted on prisoners that involved testing their reaction to pesticides and herbicides both intravenously and on their skin.

The experiments were conducted by two dermatologists at the university — one of whom is still employed by the school — between the 60s and 70s. Dr. Howard Maibach and Dr. William Epstein conducted unethical tests on men from the California Medical Facility, a prison hospital about 50 miles northeast of San Francisco.

The experiments were halted in 1977. Epstein, a former chair of the department, died in 2006. Maibach is still a member of the department.

"UCSF apologizes for its explicit role in the harm caused to the subjects, their families, and our community by facilitating this research, and acknowledges the institution's implicit role in perpetuating unethical treatment of vulnerable and underserved populations — regardless of the legal or perceptual standards of the time," Executive Vice Chancellor and Provost Dan Lowenstein said in the statement.

"Truth-telling and rebuilding trust are foundational to our commitment to reconciliation work, and in that spirit we must acknowledge the failures in our history in order to identify a path forward," Lowenstein added.

The university's investigation into the research was the first report issued by its Program for Historical Reconciliation, which was created to look into questions or concerns about the university's role in unethical conduct in biomedical and clinical research. The San Francisco Chronicle first reported the program's findings Wednesday.

Through their investigations, researchers found the two professors experimented on about 2,600 incarcerated men at the Vacaville facility, including many who were either being assessed or treated for psychiatric issues. None of the subjects had medical conditions that would have benefited from the experiments, the university said.

When the federal government called for all human subject research at state prisons to stop in 1976, the program ceased a year later.

Maibach, in a letter to the university's dermatology department, wrote that he regrets having participated in research that does not meet today's ethics standards, but believed the experiments had offered benefits to some of the patients.

"What I believed to be ethical as a matter of course forty or fifty years ago is not considered ethical today," he wrote. "I do not recall in any way in which the studies caused medical harm to the participants."

Maibach also noted that when questions first surfaced about the ethics of the research, UC San Francisco did not have an ethicist on hand. He then met with an unnamed president at the University of San Francisco, an ethicist, who at the time told him he believed the prisoners could consent to the experiments.

"Based on my frequent conversations with him, I believe that the ethicist believed unequivocally that these volunteers could provide informed consent," Maibach wrote in the letter. "He felt that these volunteers could say yes or no — in their own judgment."

Descendents of the controversial doctors questioned the findings of the university's report, believing it placed undue blame on the two men at the heart of the experiments.

Maibach's son, Edward, wrote in an email Thursday to The Associated Press that his father had been treated as a "lone ranger" who seemingly acted without knowledge or approval from university administrators. That was not the case, said the younger Maibach.

"Dr. Maibach's activities at Vacaville were known to, and endorsed by, UCSF administrators, including the UCSF ethicist," Edward Maibach told the AP.

California