A senior police officer from outside the Metropolitan Police has been brought in to take over the force's investigation into the use of undercover policing - more than a year after the £1.2 million inquiry was launched.
In light of allegations that members of the Met's Special Demonstration Squad stole dead children's identities, Scotland Yard has asked Derbyshire Police chief constable Mick Creedon to oversee the investigation, known as Operation Herne.
Home secretary Theresa May said: "Given the seriousness of the latest allegations, the Metropolitan Police commissioner Sir Bernard Hogan-Howe and the chairman of the Independent Police Complaints Commission (IPCC) have agreed it would be appropriate for a senior figure from outside the Metropolitan Police to take over the leadership of the investigation."
Mr Creedon, who has overseen previous investigations into police corruption, takes over from Met Police deputy assistant commissioner Patricia Gallan.
Operation Herne was launched in October 2011 following claims that undercover SDS officers engaged in serious sexual relationships with women they were spying on.
Twenty police officers and 11 staff are working on the operation, wading through more than 50,000 documents.
The spotlight returned to undercover officers last week when The Guardian newspaper claimed covert officers used dead children's details to infiltrate protest groups without informing the parents.
Sir Bernard said it was fully accepted that at some point it will fall to this generation of police leaders to account for past actions and accept any justified criticism that might be made.
He added: "Our priority now is to work with chief constable Mick Creedon and his team to support a thorough and impartial investigation to establish the facts about what took place."
Mr Creedon has also conducted several reviews into external forces, including the murder of 11-year-old Rhys Jones in Merseyside.