A man arrested after a blast rattled the southwest English city of Exeter on Thursday is a vulnerable young Muslim convert with a history of mental illness, police said. Police said 22-year-old Nicky Reilly was seen entering a bathroom of a crowded restaurant shortly before it was rocked by a small explosion. The incident prompted the evacuation of a large part of Exeter's city center, but Reilly - who was seriously injured in the face - was the only one wounded and is being treated in a hospital under police guard. An additional explosive was later found in the vicinity of the restaurant and defused by a bomb disposal team. It is extremely rare for British authorities to identify suspects by name before they are charged, but the local police, Devon and Cornwall Constabulary, said Reilly had been manipulated and appealed for help tracking his movements. "Our investigation so far indicates that Reilly, who has a history of mental illness, has adopted the Islamic faith," Deputy Chief Constable Tony Melville told reporters. "We believe that despite his weak and vulnerable state, he was preyed upon, radicalized, and taken advantage of." "I am taking the unusual step of releasing his photograph because we want anyone who saw him today or can help us track his movements over recent weeks to contact us," Melville said late Thursday. He then went on to give some details of Reilly's travels before the explosion, saying he took a bus from the nearby city of Plymouth to Exeter earlier in the day. Devon and Cornwall police said the incident did not appear to be part of a wider plot, although they cautioned that the investigation was ongoing. Officers were searching a property in Plymouth "connected to Reilly," Melville said. London police said it had sent a small team of counterterrorism officers to provide support for the investigation. The British Broadcasting Corp. reported that the country's domestic intelligence service, MI5, was also on the case. Terrorism-related arrests have become regular in Britain since the Sept. 11 attacks and the July 2005 suicide attacks in London that killed 52 commuters. British Home Secretary Jacqui Smith said last month that authorities were monitoring 2,000 suspects and 30 active plots, and that the threat was growing.