The firm has been besieged by negative press coverage resulting from allegations of insider dealing under former CEO Dennis Kozlowski.
Instead, day-to-day comms has been handed to Robinson Lerer & Montgomery (RLM).
Tyco chief strategy officer Brad McGee, who had been running corporate comms and was serving as chief spokesperson, is no longer involved in comms efforts.
McGee was a top aide to Kozlowski, and has been named as one of several executives who may have unwittingly received unauthorised compensation during the Kozlowski regime.
McGee received £1.25m in forgiven loans from Tyco, according to an SEC-filing the company made in September. The filing also stated there is no evidence to suggest that McGee knew these payments were unauthorised.
He is now working in the firm's finance group.
Tyco, the Bermuda-based conglomerate, refused to comment and RLM was unavailable for comment as PRWeek went to press.
But it is understood RLM was hired two days after Kozlowski was indicted on charges of tax evasion, and has since assumed nearly total control of the firm's media relations function.
Former retained agencies Kekst & Co and Brunswick both no longer work with Tyco, severing ties following the indictment.