A 30-year veteran of the Boulder County Sheriff's Office was arrested Tuesday, accused of having sexually explicit conversations with girls using his patrol car computer.Deputy Rick Ferguson, 53, is being held at the Boulder County jail on $100,000 bond.He is facing one count of Internet sexual exploitation of a child, two counts of Internet luring of a child, and one count of Internet obscenity. All are felonies. He's also facing one misdemeanor count of second-degree official misconduct.So far, the investigation has only uncovered inappropriate internet activity and no sexual contact, the sheriff's office said. Investigators believe the activity has been occurring for at least six months."It is sad and demoralizing when we have to arrest one of our own deputies. Fortunately, it is also a rare occasion. Deputy Ferguson has been a loyal and long-term employee at the sheriffs office. We were shocked to learn what was occurring, but also quick and decisive to investigate and seek prosecution," Sheriff Joe Pelle said in a statement."We are a 'Character First' organization, and the alleged actions of this deputy have violated our core values and the public trust. They do not represent the values of the almost 400 employees at the Boulder County Sheriffs Office. I am confident that accountability and openness in the handling of this matter will ensure the continued public trust and support of this office," Pelle continued.The investigation began on Nov. 17 when the sheriffs office was notified by Boulder County Information Technology employees of some unusual activity on a computer used by Ferguson.An internal investigation was initiated and it was determined that Fergusons Mobile Data Computer (MDC), assigned to his patrol vehicle, had been used for sexually explicit communication with apparent underage females, said Boulder County Sheriff's Cmdr. Scot Williams.A search warrant was also issued for his home computer.Ferguson was most recently assigned to the Civil Section of the Operations Division. He has been placed on administrative leave pending the conclusion of the investigation.Ferguson, who lives in Broomfield, has no prior arrests.The arrest affidavit was sealed because the ongoing investigation.