 Complete the following phrase:  After the incident, speculation began immediately about Hinrichs motivation and the number of accomplices, if any. An off-duty police officer had noted Hinrichs talking with a local feed store owner about ammonium nitrate and had begun an investigation. There was innuendo regarding the Pakistani heritage of the bombers roommate. Terrorism-related speculation was heightened after the explosive agent was found to be TATP, an explosive of similar manufacture, though separate makeup, to the compound used in the 