A lawyer for three activists removed from one of President Bush’s town hall events in Colorado said Thursday that the Secret Service has opened a criminal probe into whether the man who escorted them from the hall was impersonating an agent. The man was dressed in a dark suit and wore an earpiece when he escorted the three from the March 21 event. The Secret Service has said it has determined the man was not one of its agents, but a staff member with the host committee. The White House has said the man was a volunteer who probably feared the three might have disrupted Bush’s event. The man threatened the activists with arrest if they “did anything” and told them they had to leave because it was a private event. The three had tickets to the event, which they obtained from a Congressperson.