Stanford University has cleared three faculty members of any wrongdoing in dealings with a Chinese scientist who claims to have helped make the world’s first gene-edited babies.

In a statement Tuesday, Stanford said the faculty members did not participate in or have financial or other ties to the work by the scientist, He Jiankui, and had discouraged him from pursuing it.

The Chinese scientist has said he altered the genes of twin girls when they were embryos to try to give them protection against possible future infection with the AIDS virus. Scientists worldwide have condemned the work as unethical and medically unnecessary.

A spokesman for Rice University in Houston says that school is continuing to investigate the possible role of one of its faculty members.