Internal Kansas City police documents show a police unit set up to investigate crimes against children failed to properly investigate thousands of cases, with some detectives doing no work at all.

A special squad asked to clear backlogged cases found such serious problems that Police Chief Darryl Forte in January suspended nearly all of the detectives and sergeants in the Crimes Against Children Unit.

The Kansas City Star's review of internal police department memos uncovered the depth of the problem. The memos describe 148 "severely mishandled" cases, "incompetence," and evidence of efforts to cover up the problems.

A unit created in April has reviewed tens of thousands of cases.

Forte, prosecutors and child care advocates say they have seen marked improvement in investigations since the unit was overhauled.