Authorities determined Thursday three volunteers involved in a civilian project to watch the border and report illegal crossers had an illegal immigrant pose for a flippant photograph but did not hold him against his will.

The Mexican man had told sheriff's deputies he was detained and forced to pose for a picture holding a T-shirt with a mocking slogan. A review of a 15-minute videotape provided by Bryan Barton, one of the three volunteers, showed the T-shirt the man was holding read: "Bryan Barton caught an illegal alien and all I got was this lousy T-shirt." Barton was wearing an identical shirt.

"The county attorney's office reviewed all available evidence, that indicates that there was no forcible detention, therefore the case is not substantiated, and no charges are pending," said Carol Capas, a spokeswoman for the Cochise County Sheriff's Department.

The sheriff's department, Mexican Consul Miguel Escobar and the U.S. Border Patrol (search) also agreed the 26-year-old man was not detained, said Capas and Border Patrol spokeswoman Andrea Zortman.

The man, who was not identified, apparently did not initially tell a Border Patrol agent he had been detained, but did so when interviewed later by sheriff's deputies, Capas said. The man alleged when he tried to get away, the volunteers ran in front of him and would not let him go by.

The volunteers involved in Wednesday's incident identified themselves as members of the Minuteman Project (search) — a monthlong effort that has people from around the country spread out along a stretch of the Arizona-Mexico border to report undocumented migrants and smugglers.

Law enforcement officials have said they fear the project will lead to vigilante violence. Mexico's foreign relations department also pledged in the days leading up to the civilian operation to pursue all legal and diplomatic means to stop the volunteers and ensure they do not violate the rights of Mexican citizens.

The volunteers may alert authorities when they see someone cross the border, but are not allowed to detain anyone. The immigrant who complained he was held illegally was later picked up by the Border Patrol, and remains in custody.

Wednesday's incident was the first reporting any possible detention, though volunteers earlier assisted an immigrant in distress.

"The Minuteman project has created a powder-keg situation with the potential to go beyond harassment and false imprisonment to real violence," said Eleanor Eisenberg, executive director of the American Civil Liberties Union of Arizona, which has legal observers keeping an eye on Minuteman volunteers.