A private investigator who spent a decade tracking Jeffrey Epstein has given new details about the disgraced billionaire's predilection for underage girls.

In an interview with CNN on Saturday, Detective Michael Fisten claims he met with many of Epstein's victims, included one who looked like she was just nine years old.

The former homicide detective was first hired to trace Epstein back in 2009 by attorney Brad Edwards, who was representing alleged victims of the businessman in various civil suits.

Fisten told CNN that one of the most difficult moments of his investigation came when he met with a 13-year-old girl who said she had been abused by Epstein.

'She looked like she was nine [years old],' he claimed.

'She started telling me this whole story about how she tried to good a life. She was blaming herself for what Jeffrey did to her. She was in such pain.

'Nothing really fazes me after spending 13 years in homicide... but that fazed me. I teared up,' he emotionally revealed.

In an interview with CNN on Saturday, Detective Michael Fisten claims he met with many of Jeffrey Epstein's victims in the ten years that he has been investigating him

Fisten was first hired to trace Epstein (right) back in 2009 by attorney Brad Edwards (left)

Fisten says many of Epstein's alleged victims claimed the billionaire began losing interest in them as they grew older.

'Once these girls lost their braces and their pubescent look and started becoming 16 years old or 17 years old, they were too old for him', he stated.

Because the girls were so young, Fisten believes it's 'inconceivable' that those in Epstein's social circle didn't at least suspect that he was involved in something untoward.

Elsewhere in his interview with CNN, Fisten says he was left disgusted by the lenient sentence Epstein received for soliciting teenage girls back in 2008.

The billionaire pleaded guilty to the crime and was sentenced to 13 months of jail time. However, he was able to spend 12 hours a day, six days a week working at his office outside of prison.

Fisten spent time spying at the offices, and noticed a 'parade of young women' coming and going from the premises - although he could not confirm whether they were underage.

During his prison sentence, Epstein was able to spend 12 hours a day, six days a week working at his office (pictured)

His interview comes just days after attorney Bradley Edwards said he had been contacted by at least one woman who says she was summoned to Epstein's office for a sexual encounter at that time.

Deputies reportedly stood outside the building while Epstein was left unchaperoned inside, working for a business he had founded.

Members of the Palm Beach County Sheriff's Office kept a visitor log of those who visited Epstein at the office, but those records have since been discarded for unknown reasons.

The Palm Beach County Sheriff's Office announced on Friday that an internal investigation had been launched into the matter.

Sheriff Ric Bradshaw said the investigation would 'determine if any actions taken by the deputies assigned to monitor Epstein during his work release program violated any agency rules and regulations.'