As far as I know, Mr. Suzuki hasn't come back from Hawaii yet.
Literal
Suzuki-Mr. [topic-は], I [of-の] know limit [in-では], still Hawaii [from-から] has-not-come-back.
私の知る限り(では) ('as far as I know') is a set qualifier phrase: 知る (to know) + 限り (limit, extent). The 限り pattern is productive: ~限り ('as far as, to the extent that'). まだ~ていない = 'not yet X-ing' (resulting-state negative). 帰ってきていない = 'is not yet in the state of having come back.'