Andy Bonfield is leaving the drugmaker to seek unspecified ‘new career opportunities’ at the end of the month, according to a statement. A Bristol spokeswoman says his departure is “completely unrelated” to an eye-opening $275 million charge for investing in sub-prime securities, which contributed to a loss in the fourth quarter.

That blunder did lead to the departure of the controller and two of his staffers. At the time, Bristol ceo Jim Cornelius stood before a Merrill Lynch conference in New York and declared “I’m a big believer in accountability, and we’re looking for a new corporate treasurer and a couple of people under him.” However, the turn of events prompted some to speculate that Bonfield should have been the one to be let go.

In a Seeking Alpha column called 10Q Detective, David Phillips wrote “although the treasury department invests corporate funds, in the hierarchy of the company, the treasurer reports directly to the cfo (who has the fiduciary responsibility to analyze and review all the financial data and performance of the company). In other words, the ultimate responsibility of the cfo is to routinely check the corporation’s financial health and integrity.”

The Bristol spokeswoman says that, while Bonfield, 45, doesn’t have another position, “he’s not leaving the company to go elsewhere. He’s been talking to Jim since 2007″ about his role and career plans. However, she wouldn’t be more specific, other than to say Bonfield will remain for an unspecified time to help his successor, Jean-Marc Huet, 38, who previously served as cfo at Royal Numico, an infant nutrition company, adjust to his new post. To her knowledge, Bonfield will not continue as a consultant to Bristol.

One point worth noting - in its announcement, Bristol highlighted the fact Huet was “credited with initiating and developing Numico’s acquisition strategy within the consolidating baby food sector and its resulting acquisition by Groupe Danone.” Could that mean Cornelius likes the fact that Huet is experienced in mergers and acquisitions? Cornelius, you may recall, acknowledged that all options would be examined as he steers the drugmaker.

Separately, the drugmaker promoted Lamberto Andreotti from chief operating officer of worldwide pharmaceuticals to chief operating officer of the entire company. Andreotti, 57, will now be responsible for Bristol’s Mead Johnson nutritionals unit and the ConvaTec wound-healing unit, which is up for sale.