Last week we discussed how the California Public Employees’ Retirement System (CalPERS) has gone more than eight months without putting someone in charge of alternative investments, even though the system has more than $30 billion of alternative assets under management.

We also mentioned that the obvious candidate would be Joncarlo Mark, a senior portfolio manager for alternatives who had been with CalPERS since 1999. Yes, he had been involved in an overblown travel expense “scandal” last summer, but Mark was known as a well-informed staffer who didn’t hesitate to hold private equity firms’ feet to the fire.

Now Mark is no longer an option.

Multiple sources tell Fortune that Mark resigned last week, with CalPERS boss Joe Dear informing certain staffers yesterday. No word yet on what caused Mark’s decision, although it certainly couldn’t have helped that Dear recently made it clear that the new alternatives chief would come from outside of CalPERS.

One source suggests that Mark might have been worried about a new proposal from California Controller John Chang, which would require that state pension employees and board members wait two years after leaving before going to work for a firm that has done business with the pension.

It’s one of those things that sounds good in theory, but could have a chilling effect on hiring/retention at both CalPERS and fellow pension system CalSTRS. Public pension investment pros typically make far less money than their private market counterparts, and this ban literally could prevent them from getting jobs once they leave (thus compounding the low salaries). Remember, CalPERS and CalSTRS aren’t little boutiques — they are giants that do business with virtually every investment firm, bank and financial advisory in the country (particularly when it comes to alternatives).

As the proposal moves forward, don’t be surprised if Mark isn’t the last CalPERS investment pro to walk… [UPDATE: Here’s the next one to leave]

No comment yet from CalPERS.

UPDATE II: CalPERS now has confirmed Mark’s resignation. In an emailed statement, Joe Dear writes:

“Joncarlo has played a key role as a successful manager and investor for CalPERS,  In addition, as Chairperson of the Institutional Limited Partners Association, he has helped spearhead important private equity industry changes that will benefit institutional investors for years to come….

Joncarlo helped lead the CalPERS Alternative Investments Management program producing above benchmark returns during his 12 year career. His leadership also helped establish the AIM program’s reputation as a pioneer in the private equity industry. We wish him every success in his future endeavors.”