Kristi Noem did make the claim about a cannibal detainee eating himself on an ICE deportation flight, but there is no independent verification or credible evidence supporting the story.
Is the context true what Kristi Noem said: I was talking to some US Marshals who were partnering with ICE, they said they had detained a cannibal, put him on a plane to take him home, and he started to eat himself.

FactVerify
Source: factverify.com
What the Evidence Shows
The claim originates from Kristi Noem, who stated that US Marshals working with ICE detained a cannibal, put him on a plane to deport him, and that the detainee started to eat himself during the flight. Multiple recent news sources report that Noem made this bizarre claim.
However, none of the sources provide any independent confirmation or official documentation to substantiate this story. The narrative appears to be anecdotal and has not been corroborated by ICE, US Marshals Service, or any other official agency. Given the extraordinary nature of the claim, the lack of evidence or official comment makes it highly questionable.
It is possible that the story was relayed to Noem as hearsay or exaggeration. Without verification, the claim remains unsubstantiated and misleading as it presents an unverified anecdote as fact.
Therefore, while Noem did say it, the context and truthfulness of the story are dubious.