DUBLIN, Ireland — The Irish Republican Army’s reputed commander emerged from his life in the shadows yesterday, appearing in court for the first time to be charged with massive tax evasion. Irish police and prosecutors — stymied for decades in their efforts to put the alleged terror mastermind and fuel smuggler Thomas “Slab” Murphy behind bars — are now using the same approach that American authorities took to nail Al Capone: following the money trail.

The rarely photographed Mr. Murphy, 58, had been lying low since British and Irish authorities raided his border-straddling farm in March 2006 and found a vast fuel-smuggling operation that included several tanker trucks, an underground pipeline, cash and checks in bags, and laptops hidden in hay bales. They suspected he escaped at that time using a tunnel underneath the property.

On Wednesday night, detectives from the police’s anti-racketeering squad caught Mr. Murphy as he was being driven away from a Gaelic football game. Police and doctors said he feigned illness to go to a local hospital and stall for time. But early yesterday, he was charged with nine counts of failing to make tax returns.

As police escorted Mr. Murphy into Ardee District Court, he tried to shield his face with both arms held high, exposing only his bald pate. But when he walked free hours later — courtesy of Ireland’s unusually liberal bail laws — the stocky, short bachelor managed a Mona Lisa smile as photographers and camera crews captured the puffy, uncovered face of one of the country’s most feared militants. Detective Inspector Kevin Ring of Ireland’s Criminal Assets Bureau said when he read the charges to Mr. Murphy in police custody, Mr. Murphy repeatedly responded: “I want my solicitor here.”

Prosecutors argued against granting Mr. Murphy bail, noting that the alleged tax evasion involved some $3.7 million. He could face heavy fines and a possible prison sentence if convicted.