The lawmaker overseeing the probe into how Russian agents used Facebook to sway last year's U.S. election was hoping to hear from one of the company's technical experts.
Instead, Facebook will send its top lawyer and a former Washington insider to testify on Nov. 1.
Facebook said Thursday it will send Colin Stretch, its vice president and general counsel for more than four years, to testify before House and Senate panels.
Neither CEO Mark Zuckerberg nor COO Sheryl Sandberg, who met privately with lawmakers last week, will appear at the public hearings, as previously reported by CNBC.
The Republican chairman of the Senate committee investigating the matter, Sen. Richard Burr of North Carolina, has previously said he hoped the company would send someone with a technology background.
"I think it's more important that we get the person who's most capable of talking about the technical aspects of what they need to do to identify foreign money that may come in and what procedures, if any, need to be put in law that make sure elections are not intruded upon by foreign entities," Burr said last month.
Stretch's background, however, is rooted firmly in the legal profession.
Prior to joining Facebook in 2010, he was with the high-powered Washington law firm Kellogg, Hansen, Todd, Figel & Frederick for most of a decade.
Prior to that, Stretch, a graduate of Harvard Law School, was a clerk for Supreme Court Justice Stephen Breyer.
His knowledge of the Washington landscape helped him negotiate a 2011 settlement with the Federal Trade Commission, which had charged Facebook with deceiving consumers about whether it would keep their data private.