A senior police officer who headed a roads policing unit said he has "let a lot of people down" after he was filmed using a mobile phone while driving.
Superintendent Mark Thornton will be investigated after a member of the public recorded him driving away from Cleveland Police's Middlesbrough headquarters in his private car.
The video was passed to the Northern Echo newspaper which published the images.
Until recently Mr Thornton headed the Cleveland and Durham Specialist Operations Unit, which is responsible for traffic.
Its work featured on the Channel 5 TV programme Police Interceptors.
Mr Thornton issued an apology, saying: "As a serving police officer I'm more aware than most of the potentially devastating consequences of driving whilst distracted.
"This is no small thing and the consequences for pedestrians and other roads users can be fatal, which is why we have recently seen changes to the law increasing penalty points and fines for driving while using a mobile phone.
"I'm very sorry, not because of the impact on me - it's my responsibility and no one else's - but to those I feel I've let down.
"Policing is a job I love and in which I've carried out my duties to the best of my abilities over 27 years.
"I have let a lot of people down, not least myself. I will fully accept the consequences of my actions."
Cleveland Police said it will investigate Mr Thornton, who is now working in business transformation for the force.
Assistant Chief Constable Jason Harwin said: "Driving whilst distracted is serious and the information presented to the force by the Northern Echo on Monday July 17 will be fully investigated.
"We will provide an update once this is concluded."
Cleveland police and crime commissioner Barry Coppinger has made a commitment to reduce road casualties and welcomed harsher penalties introduced for drivers using mobiles.
He said: "The law applies as much to police officers as it does to anyone else.
"It's right that this officer has apologised for his actions and that Cleveland Police is now investigating the material received from the Northern Echo."