One of the country's most senior police officers has refused to apologise to the parents of dead children whose identities have been allegedly used by undercover cops.
Metropolitan Police deputy assistant commissioner Patricia Gallan told MPs she understood concerns but had to uncover the truth before she said sorry.
Addressing the Home Affairs Select Committee, Ms Gallan said Scotland Yard has received two complaints that a dead child's details were stolen by undercover cops - but admitted the parents involved had not been informed.
And she revealed that £1.25 million had been thrown at the investigation into the conduct of undercover police within the potentially rogue Special Demonstrations Squad (SDS) at the centre of the allegations.
Ms Gallan said 20 police officers and 11 staff were working on Operation Herne, the inquiry into the actions of the SDS - a unit set up in 1968 to infiltrate subversive political groups.
The team is wading through more than 50,00 documents as it investigates claims that officers formed sexual relationships with the people they were spying on, as well as allegations that dead children's identities were assumed.
She said: "At some point it will fall upon this generation of police leaders to account for the activities of our predecessors but at the moment we must focus on getting the truth."
Asked by Committee chairman Keith Vaz if she was "shocked" by reports that up to 80 officers had taken part in the practice, Ms Gallan said she could not confirm whether the numbers were accurate.
She said: "I've seen evidence of one case and very recently received a complaint of a second case and that's being investigated.
"I think more evidence will come to light of this practice. I'm very concerned by what I'm hearing and I do recognise people will be upset by what they've heard."