LOS ANGELES (CBSLA.com) — Three men were named in a federal indictment unsealed Monday in connection with a bizarre robbery and kidnapping at an East Los Angeles bank last September.

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Officials with the FBI and the Huntington Park Police Department were on hand to announce the charges in a sealed federal Grand Jury indictment from April 25 leading to the May 17 arrests of Los Angeles residents Ray Vega, 34; Richard Manchacka, 36; and Bryan Perez, 27.

The indictment alleges that Vega sought to rob a Huntington Park branch of a Bank of America on Sept. 5 by strapping an apparent explosive device to the body of his girlfriend, who worked at the branch as an assistant manager, Huntington Park Police Chief Jorge Cisneros said.

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Vega arranged for his girlfriend to wear the device in order to appear as a hostage, according to the indictment. The device was rendered safe by a Los Angeles County Sheriff’s bomb squad and was later determined to be a hoax, Cisneros said.

The indictment (PDF) also alleges that the defendants traveled to case the bank and surrounding area prior to the robbery, and that Vega arranged for the use of the vehicles to be used during the robbery.

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Investigators initially said they didn’t believe the manager knew the robbers, but they have conducted interviews to ensure she wasn’t connected to the crime, according to the Associated Press.