A Chinese biologist and two researchers from his team were sentenced to prison for illegally altering genes in human embryos, according to local media.

A court in south China’s Shenzhen city on Monday sentenced He Jiankui, a former associate professor with the Southern University of Science and Technology, to three years in prison and fined him 3 million yuans (about $430,000) for illegally conducting “human embryo gene-editing”, according to state-run news agency Xinhua.

Jiankui’s scientific work led to the births of three genetically-altered babies, he claimed.

Read more: Chinese researcher jailed for practicing gene-editing