District Councilman David Catania has publicly criticized DC Public Schools officials for their lack of progress in raising test scores, curbing truancy and improving the District's dismal high school graduation rate. But there's one dark corner where even the outspoken Education Committee chairman refuses to go.

A just-released 2009 internal memo to former Chancellor Michelle Rhee from her own outside data analyst, Fay "Sandy" Sanford, warned that the statistically improbable level of wrong-to-right erasures on the District's standardized tests implicated 191 DCPS teachers in 70 schools with "possible testing infractions."

The hitherto secret memo, marked "Sensitive Information -- Treat as Confidential," was obtained by independent journalist John Merrow, whose documentary on Rhee's now arguably tarnished legacy aired on PBS in January. Sanford warned Rhee that "88% of tested students" at Aiton Elementary School "were students of implicated teachers" who received $276,265 in bonuses from Rhee when their reading and math scores increased by 29 percent and 43 percent, respectively.

In an April 11 blog post, Merrow reported that a "reliable source" inside DCPS confirmed that both Rhee and her deputy and successor, Kaya Henderson, "discussed Sanford's memo in staff gatherings." But when asked about it on the record, both Rhee and Henderson "didn't recall" ever seeing it.

A similar number of highly questionable erasures was also discovered in Atlanta, but, as Merrow points out, the mayor and city council there called in the Georgia Bureau of Investigation and set up a team led by a former state attorney general to review more than 800,000 documents and interview more than 2,000 people, many under oath. The result: Former Atlanta School Superintendent Beverly Hall and 34 of her employees have been indicted in a major test cheating scandal.

In the District, on the other hand, three so-called "investigations" over two years -- including one by the Office of the State Superintendent of Education -- failed to even perform an analysis of the suspect erasures or examine the original test answer sheets. One first-year teacher who admitted he coached his students was fired, but no DCPS employees have been questioned under oath about test score gains so unlikely that one expert compared them to "losing a hundred pounds a month on a new diet."

Catania has the power to subpoena DCPS officials, principals and staff members who received $1.5 million in bonuses from Rhee and question them under oath about the erasures. But he wants to move on instead.