Maine State Police, Gorham police and FBI agents joined the investigation and aided in the arrest, Procopio said.

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Federal agents have joined the investigation, and the bombs were sent to an FBI lab to determine what materials were used.

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Twelve additional organizations, including the National Association of Home Builders and the American Society of Travel Agents, have already joined the coalition, and representatives from 50 groups have attended its meetings, reports co-chair Macey Davis, tax counsel for the NFIB.

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According to Reuters, Japanese intelligence authorities have joined forces with U.S. agents in an effort to identify those responsible.

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Agents from the FBI and the Iowa Department of Criminal Investigation joined the search on Saturday, authorities said.

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