Searching the DOJ homepage with the search term “spy” (to see which they have showcased) gives us 209 results, including a bunch of news around the 2009 conviction. The most resent news I found was from 2022 (https://www.justice.gov/archives/opa/pr/five-individuals-cha...) a very vague news which is actually more about harassing private citizen (presumably piggy-banking out of the anti-asian hate following Covid). The most resent news about actual spying against the US government was from 2020 (https://www.justice.gov/archives/opa/pr/former-cia-officer-a...) Alexander Yuk Ching Ma. He was actually found guilty in may 2024 (so he is missing from that Wikipedia list). The DOJ article about the conviction doesn’t use the word spy, so it is missing from my search, but here it is: https://www.justice.gov/archives/opa/pr/former-cia-officer-s....
Given the above, I think it is safe to bet that if he was arrested for being a spy, the DOJ would indeed want to showecase it. However, spies are very rare, and the likelyhood of OP’s case being a spy is very low. It is much more likely that he disappeared for other reasons.
A guy was arrested for being a PRC spy, stealing sensitive documents from GE Vernona. 2-3 years ago. I remember it because he was using stenography to embed documents in landscape photos sent via email.
They also use various means to charge people. Lying to a federal agent is a serious crime. Almost any misuse of federal funds can a a serious crime.
