In late November of last year, Chinese scientist He Jiankui revealed to the world that he had pursued a goal of genetically altering human embryos, succeeding in altering the genes of multiple babies which were then carried to term and born. It rocked the genetic science community and drew ire from many researchers around the world. Now, He may be facing a much stiffer penalty than public backlash.

As The Telegraph reports, his unexplained “disappearance” in December was actually the result of being placed in state custody. The scientist now spends his days under armed guard as the Chinese government decides how to proceed. Depending on how officials rule, one potential outcome may be execution.

His work, which was aimed at giving children of HIV-positive parents the ability to resist the disease prior to being born, resulted in at least two live births thus far. The two baby girls are reportedly healthy, but that doesn’t necessarily factor into the thinking of those investigating the research. “Playing God” by altering babies prior to birth is not only frowned upon in most countries, it’s also a crime.

He went “rogue” in his work and carried out the genetic modification despite knowing that guidelines prohibit experimenting on human embryos and then having them carried by a mother. Many of He’s colleagues in the scientific community believe that He may be charged with crimes including bribery and corruption, and that others may be implicated as the investigation moves forward.

He has reportedly received death threats stemming from his newfound fame as the first scientist to produce a genetically altered baby. The biggest threat may ultimately come from China itself, which can invoke the death penalty in cases it deems particularly serious.

It’s unclear how long the investigation might take, or when a ruling and subsequent punishment will be handed down, but we’re officially in uncharted waters.