Home Secretary Theresa May has said it may be difficult to find out who was responsible for authorising an undercover police officer to spy on the family of Stephen Lawrence.
But Mrs May assured MPs that "every effort" will be made to ensure the truth comes out in the numerous investigations and inquiries into the police's conduct after Stephen was killed.
She spoke after Labour's Diane Abbott called for an assurance the identity of whoever authorised the Special Demonstration Squad's (SDS) "spy in the Lawrence camp" will be revealed.
But Mrs May suggested that Scotland Yard's record keeping on its own investigations into police corruption may make it difficult after the review also revealed the mass shredding of key evidence in 2003.
She said: "I think everybody in this House and across the country was shocked at the findings of the Ellison review, particularly in relation to the question that there was somebody from the
Special Demonstration Squad who was, in the terms that Mark Ellison put it, effectively a spy in the camp around the Lawrence family.
"Every effort will be made to ensure that the truth comes out in relation to this."
A senior Met Police officer has been moved from his role following the publication of a report into Stephen Lawrence's murder investigation.
Almost 21 years after Stephen Lawrence was stabbed to death, the Home Secretary has ordered a public inquiry into undercover policing .