Three suspects connected to the mass kidnapping that occurred at a Mexico City bar in May will be held in preventive arrest following a ruling by a judge, officials said.

Jonathan Omar Robles Gonzalez, Pedro Francisco Paz Lopez and Fernando Fernandez Sanchez will remain in custody while prosecutors gather more evidence in the case, the Federal District Attorney's Office said in a statement.

The three suspects confessed to "their direct participation in the kidnapping of the victims" on May 26, the DA's office said.

Investigators found the remains of 13 people, all of them abducted from the Heaven bar in Mexico City's upscale Zona Rosa district, in a clandestine grave in Tlalmanalco, a city in Mexico state, last month.

The suspects told investigators they "received instructions from an individual whose alias they have provided," the DA's office said.

The judge granted a 30-day preventive arrest term so "the investigation can continue and prosecutors can take the steps needed to clear up what happened," the DA's office said.

The Federal District's Special Prosecutor's Office for Kidnappings is handling the investigation, the DA's office said.

The bodies of the people snatched from the Heaven bar were discovered by federal authorities pursuing leads in a firearms case unrelated to the Heaven bar kidnappings.

Investigators found the mass grave - covered with cement, asbestos and lime - on the La Mesa ranch in Tlalmanalco, Mexico state.

The mass kidnapping and killings were in reprisal for the May 24 murder of Horacio Vite Angel, a reputed member of the La Union de Insurgentes drug gang, by the rival La Union de Tepito group.

One of the people taken from the bar and killed, 16-year-old Jerzy Ortiz, was the son of Jorge "El Tanque" Ortiz Reyes, the jailed boss of La Union de Tepito, officials said.

Tepito is the crime-ridden downtown Mexico City neighborhood where most of the victims lived.

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