Federal officials are escalating an investigation into MF Global, the bankrupt brokerage firm run by Jon S. Corzine, as the search continues for roughly $600 million in missing customer money.

The Commodity Futures Trading Commission, which first detected the missing money last week, decided to issue subpoenas to MF Global and demanded that the firm retain any documents that may be related to the investigation, according to people briefed on the situation.

The trading commission along with the Securities and Exchange Commission and exchanges like the CME Group are examining whether MF Global diverted customer money in recent days to support its own trades in a last-ditch effort to save itself — a serious violation of federal rules.

The Federal Bureau of Investigation has also joined the inquiry, according to a person with knowledge of the case. . .