TALLAHASSEE -- The Public Service Commission lobbyist who partied at the home of a power company executive resigned Tuesday and two more commission aides were placed on administrative leave as the controversy surrounding the state's utility regulators continued to churn.

The internal turmoil surrounding the agency prompted Commissioner Nancy Argenziano on Tuesday to call for a grand jury investigation into legislative and utility company influence on the PSC. And Sen. Mike Fasano -- saying a ``disaster is in the making'' -- called for a state Senate investigation into the PSC that would force the staff and commissioners to answer questions under oath.

The PSC is grappling with growing questions about its closeness to the utilities it regulates, even as two of the state's largest -- Florida Power & Light and Progress Energy -- seek rate increases of about 30 percent beginning next year.

In the last two weeks:

• The Florida Department of Law Enforcement began investigating the PSC for potential ethics violations.

• The Herald/Times revealed that an FPL executive had asked for and received private BlackBerry messaging codes for one commissioner and two staff members, a communication method that avoids a paper trail.

• FPL executives defied a PSC order to reveal how much the company pays its top executives.

• FPL chief Armando Olivera told the PSC that his company wanted to use part of its rate increase to buy a $31 million executive jet.

On Tuesday, Ryder Rudd, the PSC's director of strategic analysis who admitted to attending a Kentucky Derby party at the Palm Beach Gardens home of FPL vice president Ed Tancer, submitted his resignation. Rudd had been supervising the commission's review of FPL's pipeline request. After he told two commissioners and the Herald/Times that he had attended the party, the PSC removed him from any FPL issues and ordered the agency's inspector general to investigate.

Inspector General Steven Stolting found that Rudd used ``poor judgment'' and may have violated PSC rules by attending the party. But Rudd said he paid Tancer $50 in cash a day after the party for food and drink he had consumed but kept no receipt, so Stolting concluded there was no way to determine whether rules were violated. Rudd had been at the PSC since 2007 and was paid $92,000.

Also Tuesday, Commissioner Lisa Edgar and Commission Chairman Matthew Carter put their two top staff advisors on administrative leave, ``pending further review,'' in the wake of a Herald/Times report that the staffers had given FPL the Personal Identification Numbers, or PINs, to their BlackBerrys. The PSC keeps no record of instant messages sent via PIN, making it possible for the utility to communicate with the regulatory agency without using the state e-mail system.

According to documents obtained by the Herald/Times, Edgar's aide, Roberta Bass -- who earns $84,724 a year -- supplied the PIN for Edgar's BlackBerry to FPL attorney Natalie Smith as well as the PIN for her own BlackBerry. Carter aide William Garner, who makes $88,924, gave Smith his own PIN number.

Another aide -- Larry Harris, who works for Argenziano -- left the commissioner's staff Saturday after telling his boss he had provided Smith with his own PIN. Harris is now seeking reassignment within the PSC.

Under state law, a commissioner who discusses a pending rate case with utility officials, known as ``ex parte communications,'' could face a $5,000 fine and removal from office. The law specifically excludes PSC staff from the ban, however. First Amendment Foundation attorney Barbara Petersen said she was ``stunned'' the staff didn't raise any concerns about ex parte communication when they were asked to provide their PINs to FPL.