The wife of Joaquin ''El Chapo'' Guzman, the imprisoned former leader of Mexico’s Sinaloa drug cartel, was arrested on Monday over her alleged involvement in international drug trafficking, the U.S. Department of Justice said.

Emma Coronel Aispuro, 31, a regular attendee at her husband’s trial two years ago, was arrested at Dulles International Airport in northern Virginia, and is expected to appear in a federal court in Washington on Tuesday.

A lawyer for Coronel could not immediately be identified. It was unclear why Coronel, a dual U.S.-Mexico citizen, was in the Washington area.

Coronel’s arrest came two years after a celebrated trial in Brooklyn where Guzman, now 63, was convicted of trafficking tons of drugs into the United States as Sinaloa’s leader, where prosecutors said he amassed power through murders and wars with rival cartels.

He was sentenced in July 2019 to life in prison plus 30 years, which the sentencing judge said reflected Guzman’s “overwhelmingly evil” actions. Guzman was sent to ADX Florence in Colorado, the nation’s most secure “Supermax” prison.

Coronel was charged in a one-count complaint with conspiring to distribute heroin, cocaine, marijuana and methamphetamines for unlawful importation into the United States.

Prosecutors said Coronel also conspired to aid her husband in his July 2015 escape from the Altiplano prison in Mexico, when he dug a mile-long tunnel from his cell, and began plotting a second escape following his capture by Mexican authorities in January 2016.

U.S. and Mexican efforts to fight drug trafficking had become strained when the Justice Department brought drug charges in October against former Mexican Defense Minister Salvador Cienfuegos.

The Justice Department unexpectedly dropped that case the following month and let Cienfuegos return to Mexico, in a bid to restore trust in the countries’ security ties.

Cienfuegos was exonerated two months later when Mexico dropped its own case.

Tomas Guevara, an investigator in security issues at the Autonomous University of Sinaloa, said Coronel’s arrest might be part of a “pressure strategy” to prompt cooperation from Guzman.

A Mexican official familiar with Coronel’s case, who asked not to be identified, said her arrest appeared to be solely a U.S. initiative, and that Coronel was not wanted in Mexico.

Reporting by Jonathan Stempel in New York, Eric Beech and Mark Hosenball in Washington, and Dave Graham and Lizbeth Diaz in Mexico City; Editing by Jonathan Oatis and Stephen Coates / REUTERS