The roundup of what a Tanzanian police spokesman called "dubious characters" may even be motivated by the government's concern too nip in the bud any signs of Islamic militancy. "It appears the Tanzanians have had these people under surveillance for some time and are using the bombing as a pretext to arrest them," says TIME reporter Clive Mutiso. A Tanzanian official's statement that "we cannot say we have got somebody who is really responsible" but "we think we are doing well" underlines the grounds for skepticism. U.S. investigators continue to probe for the forensic evidence crucial to establishing a "fingerprint" modus operandi that could help identify the bombers: Reports from Nairobi that the terrorists used the plastic explosive Semtex appear to confirm the notion that the attackers weren't amateurs.
Washington is playing down the significance of Tanzania's arrest of 30 people in connection with Friday's bomb attack. "The State Department isn't setting too much store by these arrests because the attacks were clearly carried out by professional terrorists," says TIME correspondent Douglas Waller. "They'd have had an escape plan rather than be waiting around to be arrested."