Stanford launched the investigation following media reports that three of its faculty—more than at any other institution—were aware of He’s plans to create the gene-edited children. They are William Hurlbut, a physician and medical ethicist who interacted extensively with He over many months; gene-editing specialist Matthew Porteus; and Stephen Quake, a biophysicist who holds a powerful role as co-president of the $600 million Chan Zuckerberg Biohub, as well as being He’s former postdoc advisor.

He held a position as a postdoctoral researcher in Quake’s laboratory beginning in 2011 but returned to China the following year.

It is not known what information Stanford is seeking from its faculty, but the investigators may hope to clarify whether any Stanford employees assisted He or had financial entanglements with him, or what steps they could have taken to stop him.

The Stanford investigation, which one person familiar with it said would be conducted by a third party, is the second to be undertaken by a US university in the aftermath of the scandal, which deeply shook the scientific community and highlighted failures in scientific self-governance.

In November, Rice University said it would carry out a “full investigation” into the role of Michael Deem, a bioengineering professor and onetime graduate advisor to He. Deem played a direct role in the research, including meeting with prospective patients in China, the AP reported, and added his name as senior author of an unpublished manuscript.

Deem’s lawyers have contested his reported role, telling the Houston Chronicle that “Michael does did not do human research and he did not do human research on this project.”

University-led investigations are typically private, toothless affairs with few consequences for important faculty, especially those who pull in millions in grants. The question of research involving human subjects is a critical one, however, in part because serious violations can endanger a university’s federal research grants.

On January 21, the Chinese news agency Xinhua published a summary of the investigation into He, indicating there could be serious legal consequences for the Shenzhen scientist, who was fired by his university the same day. Citing unnamed investigators, the report said that starting in 2016 He “privately organized a project team involving foreign personnel, deliberately evading supervision” and using CRISPR for prohibited purposes.

The phrase “foreign personnel” seemed no accident and may have helped prompt Stanford’s investigation, which got under way in late January. To some, the focus on foreigners suggests that China might try to spread the blame for the incident away from He and China’s weak oversight system. Chinese investigators could eventually disclose details about the involvement of US scientists, perhaps showing it was more extensive than currently understood.

Another view, also expressed by several scientists, is that He is unfairly being isolated and demonized while in fact a number of US scientists advised him or provided encouragement for his undertaking. These people worry He could be severely punished in China’s swift and opaque judicial system. If so, they say, his confidants now have a duty to speak up and disclose their role, despite risks to their own careers.

What is certain is that He widely telegraphed his plans. He and his students e-mailed numerous scientists and ethicists seeking input. A much smaller number, including Stanford’s Quake and Craig Mello, a Nobel Prize winner at the University of Massachusetts Medical School, knew by the middle of last year that He had already established pregnancies.

Although Mello told He that he disapproved of the effort to make babies, according to e-mails, he continued to advise him until the news of the twins broke. Mark Shelton, a communications official with the University of Massachusetts, said the school was not planning any inquiry into Mello’s role in the research.

Starting in 2017, He began to widely advertise his interest in creating gene-edited humans. He did so at a private gene-editing meeting in February of that year held at the University of California, Berkeley, which was co-organized by Hurlbut, the bioethics scholar at Stanford, and which drew science and policy luminaries.

On his blog, He described “fierce debates” at the meeting as people exchanged views on how gene editing should be applied to humans. Hurlbut continued to have extensive conversations with He, offering ethics advice, but claims the Chinese scientist never told him there were actual pregnancies under way, although Hurlbut suspected it.

A question in the background of the Stanford inquiry is why the US scientists in the know did not blow the whistle. Porteus told an audience at Stanford Law School this January that He visited him on campus in early 2018 and shared his plans to “generate a human being” resistant to HIV. Porteus says he criticized the undertaking but, as a fellow scientist, also promised to keep it secret. “Our culture is to respect confidentiality,” Porteus said at the event.

Far less is publicly known about what interactions He had with Quake, a prominent inventor of gene analysis techniques in whose Stanford lab the Chinese scientist worked during 2011 as a postdoc. The pair published a paper together unrelated to CRISPR, but He’s time at Stanford was cut short when he was recruited back to China to set up a lab in Shenzhen.

As a rising star at home, He was in a position to be generous with offers of travel to China, joint research, and financial incentives to create ties to US scientists. He controlled a startup, Direct Genomics, which had raised several million dollars to develop a gene analysis technique previously invented by Quake. Mello, of the University of Massachusetts, agreed to join the company’s advisory board and traveled to China for meetings, including one that occurred within days of the birth of the twins.

Correction: An earlier version of this article misstated the professional specialties of William Hurlbut. He is a physician, medical ethicist, and adjunct professor in the Department of Neurobiology, not a medical ethicist and theologian.