A Dallas police officer accused of aggravated sexual assault against an 8-year-old girl has been terminated from his job, the department announced Tuesday.

Ryan Ramirez, 33, is under investigation by the Kaufman County Sheriff's Office and is a family friend of the victim, investigators say.

The Dallas Police Department said Ramirez was initially placed on administrative leave after his July 15 arrest, and Chief David Brown ordered his firing after a disciplinary hearing Tuesday.

Ramirez was hired in January 2008 and assigned to the Narcotics Division.

The child's identity will not be released due to her age and because she is believed to be a victim of a sex crime.

The sheriff's department has turned the case over to the Kaufman County District Attorney for referral to the grand jury, and further details about the case have not yet been released.