Federal regulators escalated their antitrust investigation of Google on Thursday by hiring a prominent litigator, sending a strong signal that they are prepared to take the Internet giant to court.

The Federal Trade Commission is examining Google’s immensely powerful and lucrative search technology, which directs users to hundreds of millions of online and offline destinations every day. The case has the potential to be the biggest showdown between regulators and Silicon Valley since the government took on Microsoft 14 years ago.

Then as now, the core question is whether power was abused. The agency’s inquiry has focused on whether Google has manipulated its search results, making it less likely that competing companies or products appear at the top of a results page.

A spokeswoman for Google, which is based in Mountain View, Calif., declined to comment.

Federal Trade Commission officials cautioned that no decision had been made about whether to bring a formal case against Google. But the hiring of Beth A. Wilkinson, a former Justice Department prosecutor who played a lead role in the conviction of the Oklahoma City bomber Timothy McVeigh, immediately catapulted the investigation to another level. The agency has hired outside litigators only twice in the last decade.