A mystery that’s been wafting about for three months was finally solved this week when Google named Vanessa Wittman CFO of its new mobile-technology division.

Wittman announced her impending resignation from Marsh & McLennan Cos. on February 29 and said she’d be moving to Google. But neither she nor the Silicon Valley giant would say what role she would fill.

As it turns out, Google was waiting until its $12.5 billion cash purchase of Motorola Mobility Holdings was finalized, which didn’t happen until Tuesday of this week. The deal was announced last August but was held up by government approval processes, the last of which was completed over the weekend by Chinese antitrust authorities.

Google, in fact, is turning over almost the entire leadership team of the Motorola unit, including its CFO, Sanjay Jha. Dennis Woodside, who had been president of Google’s America’s region, now takes the reins.

Wittman, who compiled a remarkable career before turning 30, gained fame in 2002 when she became CFO of Adelphia. The company had been one of the country’s largest cable-television operators before an accounting scandal brought it down and earned its top executives long prison sentences. Her task was to wind down the company and sell its assets, an experience she’s referred to as a large dose of “extreme finance.”

Google did not respond by press time to a request for an interview with Wittman.

Meanwhile, the appointment of Woodside could indicate Google is going to make a run at achieving a dominant position in the mobile advertising market, Wired reported yesterday. While he’s never worked on a hardware project or held a job in the consumer electronics or mobile industries, he is a former mergers-and-acquisitions lawyer who has overseen multibillion-dollar revenue growth in Google businesses, particularly on the advertising side.