Representative Steve Stockman and three of his aides have been subpoenaed by a federal grand jury.
Stockman notified Congress of the subpoena but did not reveal the nature of the federal investigation. Stockman lost a primary election for Senate and is retiring after two terms representing the Houston area. [...]
Stockman and three aides submitted formal statements to the House clerk Wednesday acknowledging the subpoenas and declaring that they are complying with them.
While it's not clear what the subpoena is related to, it may be related to this:
This summer, the Office of Congressional Ethics had urged the House Ethics Committee to investigate $15,000 in campaign contributions that Stockman accepted from two of his staffers. The OCE found Stockman may have violated federal laws and House ethics rules by accepting the donations. The independent watchdog agency also accused Stockman of impeding its investigation.
Of course that's just one possibility among many for a man who, as you may recall, operated his failed campaign out of an condemned hellhole.