Joe Sullivan. Ariel Zambelich/WIRED

Joe Sullivan, the Facebook executive in charge of keeping the social network’s 1.3 billion users safe, is leaving to become Uber's first chief security officer.

The move is a major talent grab by the $40 billion car-hailing-app company, and it comes as cofounder and CEO Travis Kalanick grapples with security concerns escalating so rapidly they threaten to slow Uber’s momentum.

In particular, serious accusations involving its drivers are piling up. District attorneys in both San Francisco and Los Angeles have filed lawsuits against the company, alleging its background checks aren’t adequate. In December, a woman in New Delhi, India accused an Uber driver of raping her, and the woman has since filed a lawsuit.

Meanwhile, similar allegations have cropped up in cities across the United States including Chicago and Boston. In London, a woman alleged an Uber driver sexually harassed her and asked her to perform oral sex. Just two days ago, the Denver Post reported that an UberX driver had been arrested for attempting (unsuccessfully) to break into a passenger’s home after dropping her at the airport.

That’s enough to scare anyone into thinking twice before tapping the Uber icon. And it’s why Kalanick recruited Sullivan, who starts in late April and will report directly to him. Sullivan, 46, will head up Uber’s efforts to keep passengers and drivers safe, and he’ll also oversee global cybersecurity. At Facebook and during an earlier stint at eBay, Sullivan dealt in online security, not physical security. But one often plays into the other, and in addition to his work in Silicon Valley, Sullivan can draw on years of experience as a federal prosecutor.

In a blog post announcing Sullivan’s hire, Kalanick wrote: "We see opportunities ahead not just in technology, through biometrics and driver monitoring, but in the potential for inspiring collaborations with city and state governments around the world." It’s a tall order that will require the company, which has often found itself at odds with city regulators and law enforcement, to work more closely with them.

From 9/11 to Facebook

After more than two decades spent working to combat cybercrime and keep people safe in both the public and private sectors, Sullivan may be uniquely qualified for this challenge. After getting a law degree from the University of Miami, he spent eight years with the United States Department of Justice. As the first federal prosecutor dedicated full-time to fighting high-tech crime, he worked on many high profile internet cases from digital evidence aspects of the 9/11 investigations to economic espionage and child predator cases.

In 2002, he joined eBay where he oversaw security for both the Skype and Paypal units. He grew adept at managing the fine line between complying with authorities, and holding back some information to protect users. During six years at Facebook, he was the guy responsible for weeding out the miscreants from among the social network’s users. He navigated the company’s relationship with law enforcement and investigations, and he managed the teams responsible for information security and product security, among other things.

Sullivan has long been interested in the security challenges facing the companies that compose the sharing economy. In an interview with Fortune last year, he mentioned that he advised Airbnb on trust and safety issues, explaining: “It’s a fun side project.”

New Code of Conduct

At Uber, he’ll work closely with Katherine Tassi, who is tasked with safeguarding rider data as the managing counsel of data privacy. Phil Cardenas, the company’s head of global security, will report to him.

Uber has been amping up its safety efforts in recent months. Already, it has a fraud engineering team that reports to CTO Thuan Pham. Cardenas manages compliance and incident response teams as well as a group of people who work with law enforcement.

In a March 25 blog post, Cardenas said Uber will form a safety advisory board of independent experts who will review its practices and advise on future safety features. He also said Uber plans to improve its background checks on drivers, and it has established a new code of conduct.