In a television ad now airing, paid for by an independent expenditure group called the California Senior Advocates League PAC and attacking Sen. Fran Pavley, an announcer asserts, "While Pavley voted to raise our taxes, she pays none on her six-figure salary."

While that bald-faced assertion is being made, a screen shot shows a photo of Pavley alongside a headline that reads "$261,000 tax free salary."

The assertion is preposterous. Legislators are paid an annual salary of $90,526, and they pay taxes just like everyone else -- federal income taxes, Social Security taxes, state income taxes and the rest. In fact, the Pavley family's tax attorney attests in an email shared with me today that Pavley and her husband, Andy, paid $16,797 in federal income taxes in 2011, for an effective tax rate of 16.6 percent. In addition, they paid state income taxes of $5,925.

So where does this "tax free salary" assertion come from?

It's very hard to get an answer. The PAC lists no address on its forms filed with the secretary of state. The phone number listed is that of a Sacramento CPA. When I called that number today, I was told by the receptionist that the CPA "doesn't talk to the media at all" in regards to questions about the PAC.

Yesterday, I was able to track down a Sacramento political consultant who does some work for the PAC, and was referred to the PAC's legal counsel. I left a message at that law office this afternoon.

For now, we're left to try to decipher on our own what the ad from this shadowy group means to say. There is a small citation that appears at the bottom of the screen for less than two seconds that references Assembly and Senate records dating back more than a decade. Presumably, then, the reference is to the per diem payments out-of-town legislators receive while they are in Sacramento on legislative business. Again, presumably, the $261,000 figure refers to the cumulative total of per diem payments made to Pavley during the six years she was in the Assembly and four years in the Senate. That would work out to a little more than $2,000 a month, which is about what the average monthly per diem payments would be.

Per diem payments are in fact tax-free, but they are not "salary." They are, in essence, travel expense payments. Like most out-of-town legislators, Pavley lives in her district -- at the family's longtime home in Agoura Hills. She keeps an apartment in Sacramento in which she stays while working at the Capitol. The purpose of per diem pay is to cover expenses such as out-of-town lodging.

No one listening to that commercial would be able to jump through all these hoops to dissect what is being asserted in the ad. All they take away from it is a lie -- that Pavley makes a $261,000 "salary" and that it is "tax free."

If no one from the California Senior Advocates League PAC can be tracked down to account for the ad, what about Pavley's opponent, L.A. prosecutor Todd Zink?

Rachel Culbert, spokeswoman for the Zink campaign, told me today, "We really don't have any information about the ads. We have no control over them."

Under the law, that's true. Independent expenditure committees cannot coordinate with candidates.

But if there is no one to publicly speak for the independent expenditure committee, and the candidate on whose behalf the ad is being run won't comment, the question in the headline above remains unanswered.

Who's accountable for this lie?