A committee of MPs have condemned the "woefully under-equipped" watchdog charged with investigating police brutality and cover-ups.
Chairman Keith Vaz said the Independent Police Complaints Commission had too often left the public "frustrated and faithless."
Although nearly a quarter of officers were subject to a complaint last year, just a handful of those allegations were investigated, Mr Vaz said.
"The Commission is on the brink of letting grave misconduct go uninvestigated."
He called for the IPCC to have more powers including statutory orders, follow-up investigations and immediate control of potential crime scenes.
The home affairs committee also said the IPCC should be given new powers to investigate private contractors like G4S, Capita, Mitie and Serco, which were now paid for activities formerly carried out by police.