Since then, the case has made few advances, with even basic information requests languishing for months, according to two other people who have reviewed the latest case files.

But the stronger investigation in Mexico, begun early last year by the attorney general’s office, amassed enough evidence months ago to charge suspects, according to three individuals who have reviewed the case or been briefed on it. The political pressures are too great, they said, for the case to move forward.

The suspects worked for Mexico’s national oil company, Petróleos Mexicanos, known as Pemex. In its settlement with other countries, Odebrecht acknowledged paying millions in bribes to officials at the Mexican oil company. And Mexico’s former attorney general, Raúl Cervantes, who personally oversaw the case during his tenure, even traveled to Brazil to discuss the evidence that the authorities had gathered there.

Mr. Cervantes’s decision to take such an active role in the case caught the attention of many inside the attorney general’s office — and far beyond it. Some hoped it was a sign that the scandal would not be ignored. Others feared that because the attorney general is appointed by the president, his independence could be compromised.

The attorney general’s office did not respond to repeated requests for comment.

Nothing has happened in Mexico — at least not to Mexican officials. The nation has issued an administrative sanction against Odebrecht, prohibiting it from doing business in the country for the next several years.

But no Mexican officials have been charged with accepting bribes, and Mr. Cervantes, who stepped down last October, has said publicly that the investigation was complete.