A former driving instructor has been jailed for 18 years after raping a 14-year-old girl and sexually assaulting a number of his pupils.
Martyn Rees was arrested by Staffordshire Police after attacks in Newcastle-under-Lyme, Cheshire and Manchester between February 2015 and March 2018.
Detectives from the force's Child Protection and Exploitation Team (CPET) seized electronic equipment, and 29 video clips of female students were found on his phone.
Officers said one video featured a teenager who was unconscious while Rees sexually assaulted her.
The 37-year-old admitted nine offences in July and December last year - assault by penetration, two counts of sexual assault, four counts of making an indecent image and two counts of possession of cannabis.
In March, Rees, of West Avenue, Stoke-on-Trent, was convicted of rape and two charges of sexual assault on a 14-year-old girl, sexual assault, two charges of attempted sexual assault, and six charges of making indecent images and two counts of possession of extreme pornography.
On Thursday he was jailed for 18 years, handed an indefinite Sexual Harm Prevention Order and will be required to sign the sex offenders register for life.
Passing sentence at Stoke-on-Trent Crown Court, Judge David Fletcher said: "Rees had a disturbing and unhealthy interest in young children and extreme pornography."
Detective Constable Andrew Hayes, from CPET, said: "Today's sentence reflects just how dangerous Martyn Rees is. Over a number of years Rees offended against vulnerable young females, abusing his position as a driving instructor.
"The successful conviction was only possible due to the bravery and courage of the victims.
"They were brave enough to report what had happened and had the courage to have their voices heard in court."
Mr Hayes added: "I hope this is a positive message to victims of similar offences that you will be listened to, you will be believed, you will be supported and the offence will be investigated."