A police officer and scout leader who sexually abused boys and young men has been convicted of 40 offences.
Allan Richards, who served with West Midlands Police for 31 years, assaulted 17 people between 1976 and 2013. His youngest victim was eight.
The 54-year-old, who worked as a police constable between 1980 and 2011, kept a list of boys he was attracted to.
West Midlands Police has apologised to Richards's victims and said it could have done more.
The attacks took place at scout camps, swimming pools and other locations.
The court heard Richards used a police database to access information about young men.
He indecently assaulted scouts inside tents and told some victims he was touching them to eliminate them from a criminal investigation. One assault was committed in a police station.
Richards, formerly of Thaxted Road, Birmingham, was convicted at Birmingham Crown Court of nine indecent assaults against six boys. He will be sentenced at a later date.
He was found guilty earlier this year of a further 31 sex offences against other boys, including two rapes from the 1970s.
One victim, who was eight when he was abused, said he felt "sick, emotional [and] quite frightened" giving evidence during the trial.
"As soon as the police said to me they wanted to talk about an incident, or possible incident, when I was in the cubs, it was like opening up Pandora's box - everything came flooding back," he said.
"It's something I'd put in a box when I was very young, thought I'd locked it away, but [when the police came] it came springing back out instantly."
The court heard that Richards was questioned after concerns about him were raised in both 2000 and 2004.
But, although he was barred from contact with the public, he avoided prosecution because West Midlands Police said the force was advised there was not enough evidence for a conviction.
Analysis: Phil Mackie, BBC News
Because he pleaded not guilty to all of the charges his victims had to come to Birmingham Crown Court to give evidence.
One of his two rape victims, who is now an adult, told me "it was horrific" to see the man who "turned my life upside down".
If West Midlands Police had fully investigated complaints made by victims in 2000 and 2004 Richards might have been brought to justice earlier.
Detectives didn't search his home, and didn't find the evidence that eventually convicted him.
In 2014 a third investigation was launched. This time detectives did a thorough job, searched his home and found the diaries in which he documented the abuse, which lasted more than three decades.
Assistant Chief Constable Alex Murray apologised to the victims and said Richards had preyed on children, both on duty and off duty.
He said: "In retrospect, when I look back at those investigations, yes we took action, yes we spoke to the victims. Could we have done more? I think we probably could have done."
The Scout Association condemned Richards' actions and said it was pleased he had been found guilty.
The Independent Police Complaints Commission, which is investigating, said the fact Richards was able to abuse his position as a police officer while committing many of his crimes was "of great concern".
It said: "His victims will not be alone in wanting to know if opportunities were missed, and our independent investigation will examine whether more could have been done by the force to uncover his activities sooner."
West Midlands Police and Crime Commissioner David Jamieson said it was "extremely worrying" Richards had been able to remain a police officer until 2011.
He said he had commissioned a report into the force's failings to ensure it would not happen again.
"The force has very serious questions to answer and I will make sure the chief constable provides the answers the public - and Richards's victims - deserve," he said.