(Reuters) - Jury deliberations in the U.S. trial of accused Mexican drug cartel boss Joaquin “El Chapo” Guzman were expected to stretch into a fourth day after jurors asked to review days’ worth of testimony from key prosecution witnesses.

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Guzman, 61, is accused of trafficking tons of cocaine, heroin, marijuana and methamphetamine into the United States as leader of Mexico’s Sinaloa Cartel. He twice escaped from prison in Mexico; if convicted, he will face a U.S. prison sentence of up to life.

The 11-week trial in federal court in Brooklyn, in which more than 50 witnesses testified, offered the public an unprecedented look into the inner workings of the cartel, named for the state in northwestern Mexico where Guzman was born in a poor mountain village.

The defense has argued Guzman was set up as a “fall guy” by Ismael “El Mayo” Zambada, a Sinaloan drug kingpin who remains at large.

On Wednesday afternoon, jurors asked to review the testimony of Zambada’s brother, Jesus “El Rey” Zambada, and son, Vicente Zambada, as well as of Guzman’s former top lieutenant, Damaso Lopez. U.S. District Judge Brian Cogan told them they would get transcripts of the testimony as soon as they were ready.

The three witnesses pleaded guilty to U.S. charges and agreed to testify against Guzman. All of them spoke at length about Guzman’s alleged drug trafficking.

The jurors also asked whether the killing of drug cartel members by members of a rival cartel for personal reasons counted as a “drug trafficking crime.”

One of the 10 criminal counts against Guzman, engaging in a continuing criminal enterprise, includes the charge that he conspired to murder cartel enemies. The jury gave no indication of whether their question related to any particular murder.

Cogan instructed the jurors that if a drug cartel member was murdered for “wholly personal” reasons unrelated to drug trafficking, it was not a drug trafficking crime.

The 12 jurors appeared relaxed and even cheerful as they entered the courtroom to receive Cogan’s instructions.

They had already asked on Tuesday to review the testimony of two other witnesses who were cooperating with prosecutors, Colombian drug traffickers Jorge and Alex Cifuentes, as well as part of Jesus Zambada’s testimony about manufacturing methamphetamine.

The jurors left court around 4:15 p.m. EST on Wednesday, and were expected to return at about 9:30 a.m. on Thursday. They began deliberating early Monday afternoon.