"What do they need from Harvard to determine if an individual has violated their visa?"
Because the administration has chosen to include define a range of activity which is not obvious from other sources as incompatible with visa status, including membership in certain student organizations.
> Do they not have evidence of a crime?
"Crime" is not the issue, and, no, they don't, that's the problem -- they want information from Harvard with no basis other than the fact that students are on a visa, so that they can use it for fishing expeditions for excuses to deny visa status.
Because the administration has chosen to include define a range of activity which is not obvious from other sources as incompatible with visa status, including membership in certain student organizations.
> Do they not have evidence of a crime?
"Crime" is not the issue, and, no, they don't, that's the problem -- they want information from Harvard with no basis other than the fact that students are on a visa, so that they can use it for fishing expeditions for excuses to deny visa status.