The FBI is attempting to trace up to 90 potential victims of an American paedophile who taught at London's prestigious Southbank International School from 2009 until last year.
William Vahey's crimes were uncovered last month and investigators say some victims may not even know they were abused, as the teacher drugged many of the boys he targeted.
The 64-year-old, who typically taught in international schools, was found dead from an apparent suicide in Minnesota last month, after confessing to drugging male pupils with sleeping pills before sexually abusing them on field trips.
Police who searched his computer found images of at least 90 boys aged from 12 to 14, who appeared to be drugged and unconscious. The children are thought to be Vahey's students, as the photos were catalogued with dates and locations going back to 2008 that corresponded with overnight field trips.
The FBI's Special Agent Patrick Fransen said: "I've never seen another case where an individual may have molested this many children over such a long period of time.
"I'm concerned that he may have preyed on many other students prior to 2008."
The names of around 100 firms and individuals who allegedly used corrupt private investigators was handed from Serious Organised Crime Agency (Soca). Soca has come in for criticism over the way it has dealt with the case sparking a row over transparency.
In a letter to the Home Affairs select committee information Commissioner Christopher Graham wrote: "The documentary evidence we hold in relation to these clients is considered significant, and this gives us the best opportunity of instigating criminal proceedings."
The "blue-chip hacking" list was drawn up at the request of the committee and relates to Soca's Operation Millipede, which led to the conviction of the private detectives jailed for fraud in 2012.
Britain's data watchdog is poised to call in the FBI to investigate the so-called blue chip hacking scandal, it has been reported.
Information Commissioner Christopher Graham has told MPs he will contact United States authorities after finding a number of companies contracted private investigators in the UK to hack, blag and steal sensitive data, according to the Independent.
Mr Graham has also revealed that "Demand for Access" notices are being prepared so investigators can get at further evidence from the 11 clients in Britain.
They hired four private detectives jailed two years ago after accessing bank account and mortgage details, medical records and information from the Police National Computer, it added.
A dust mask and other items seized from the martial arts studio of a Mississippi man charged with sending letters laced with a deadly poison to President Barack Obama have tested positive for ricin, according to a court document released on Tuesday.
Tupelo martial arts instructor Everett Dutschke is also charged with sending poisoned letters to two other public officials.
Records seized by the FBI also showed that he ordered castor bean seeds, used to make ricin, from eBay, FBI Special Agent Stephen Thomason said in an eight-page affidavit.
The FBI is investigating how hackers were able to send out a bogus tweet on the Associated Press's Twitter feed that falsely said President Barack Obama was injured in two explosions at the White House.