A man suspected of being responsible for multiple bank robberies in Los Angeles County was indicted by a federal grand jury last week, law enforcement officials have announced.

William Joseph Allen, 32, of Los Angeles, was charged in an eight-count indictment filed in U.S. District Court in Los Angeles with bank robbery and attempted bank robbery. The indictment charges Allen with four bank robberies in Los Angeles, including a Nov. 28, 2011, robbery at the Bank of America at 8655 Beverly Blvd and a Jan. 4, 2012, robbery at the Wells Fargo at 10789 W. Pico Blvd.

Detectives with the Santa Monica Police Department identified Allen as a suspect in the series of robberies that had been linked to the “Explosives Threat Bandit” after developing forensic evidence collected at a bank robbery on March 29. Once Allen was identified as a suspect, investigators conducting the joint investigation obtained an arrest warrant. Allen was apprehended on April 17 in downtown Los Angeles by officers with the Los Angeles Police Department’s Central Division.

During the early robberies linked to the Explosives Threat Bandit, the suspect left behind a device made up of electronic components and various wiring. The suspect advised the victim teller that someone outside the bank would detonate the device, indicating explosives were contained within the device. During some of the robberies, the suspect would indicate or state that he had a bomb.

The device and associated threats required bomb squads in Los Angeles County to respond to the banks in order to render the situation safe, a process that lasted several hours and required the involvement of multiple personnel.

In other robberies, witnesses described a handgun brandished by the suspect. During the robberies, the suspect made oral demands and used written notes that he passed to the teller, demanding cash. Some of the notes indicated that the suspect had a friend outside the bank who was monitoring a police frequency and whom he would advise to “press a button” if the victim did not comply. One note contained the phrase, “establishment will not exist.”

Allen, who is being prosecuted by the U.S. Attorney’s Office, is being held in federal custody awaiting trial. This investigation was conducted by the Los Angeles Police Department, the Los Angeles County Sheriff’s Department, the Santa Monica Police Department, the El Monte Police Department, the West Covina Police Department, the Baldwin Park Police Department and the FBI.