A sergeant in the Bexar County Detention Unit was arrested by San Antonio Police today on a drunk driving charge.  Police say Stephanie Vega, 27, was stopped when an officer noticed her speeding down Loop 410 near I-10 early today.

  She was arrested and taken not to her own jail, but to central booking in the Magistrate's office.  Police say Vega flunked a roadside sobriety test and the arresting officer 'observed signs of intoxication.'

  The Sheriff's department released a statement confirming the arrest.

  "The Sheriff's Office takes this matter very seriously and is conducting an internal investigation regarding the circumstances of the incident," the statement said.  "Once the investigation is complete, the agency will determine the appropriate course of action."