A private investigator hired by the family of teacher John Wunderle’s victim to find out if he was still seeing their daughter has described it as the “most rewarding work you can do”.

On Friday 35-year-old Wunderle was jailed after pleading guilty to five sexual offences involving the teenager.

But it could have been a different story, as Snaresbrook Crown Court heard the teacher at Bancroft’s School, Woodford Green, was planning to run away to Amsterdam with the 15-year-old.

The teenager’s parents turned to the Essex Investigator after reading about his work in the Recorder’s sister paper, the Barking and Dagenham Post.

Despite having been charged with the offences, they suspected Wunderle was breaching his bail and continuing to contact and even meet up with the teenager.

The investigator fitted spying software to a mobile phone bought for the girl, which allowed the family to track her calls, texts and internet search history from a computer.

He also paid a night-time visit to Wunderle’s flat in Waltham Abbey – to fit a tracking device to the underneath of his car.

But after following the pair for just over a week, alarm bells rang when the teenager left for work – despite text messages showing she did not have a shift that day.

And the tracker under Wunderle’s car showed he was parked just yards from her house.

“I followed her up the street, then she crossed the road and climbed into the back of his car,” he said.

“She covered herself over with the blanket.”

It was then the investigator knew he had to act.

“Wunderle had gone no more than 15 metres and I blocked him into a dead end,” he said.

The investigator confronted Wunderle in the driver’s seat with a video camera, taking the keys out of the ignition.

“It’s difficult to maintain my professionalism when face-to-face with a child abuser, but I have a job to do.”

The investigator called police and Wunderle was arrested.

Visit essexinvestigator.co.uk.