He was a low-level aide in the Trump Campaign and never met the boss. He did, however, have connections with Russia, though he has repeatedly denied he did their bidding.
A former naval-officer-turned-energy consultant, Page came under fire last year after reports emerged that he had met with high-level associates of Russian President Vladimir Putin in Moscow in 2016. While Page denied those meetings occurred, the Trump campaign distanced itself from the adviser not long after, with former officials saying that Page and Trump had never met. –Politico
Comment: It is unclear if his refusal is related to the Mueller investigation, but it could well be. Page, Mike Flynn, and Paul Manafort are all in the crosshairs, according to media reports.
Anybody facing potential indictments would be advised by lawyers not to say anything.
Page is a small fish. Presumably, Mueller’s team would want information from him, but it is not clear if he has any or knows about others approached by the Russians.