D.C. Council Chairman Kwame R. Brown told colleagues Thursday their Trust questions will have to wait. (Katherine Frey/THE WASHINGTON POST)

The Children and Youth Investment Trust Corp.allegedly issued grants to nonprofit organizations that then kicked back hundreds of thousands of dollars in public funds to Thomas. The group has been under a spotlight since graft allegations were first leveled last summer against Thomas, who pleaded guilty to theft and filing false tax returns earlier this month.

U.S. Attorney Ronald C. Machen Jr. said following Thomas’s plea that the federal investigation into the scheme continues. Since then, several accomplices have pleaded guilty to helping to cover up his crimes.

Brown’s letter asks his colleagues to refrain from making inquiries into past Trust transactions while the probes are underway, citing a “request from law-enforcement authorities” that legislators limit their inquiries to “general questions about process, procedures, and operations.”

More specific questions will have to wait for May 1, the letter said. Thomas’s sentencing is set for May 3.

Lawmakers asked D.C. Auditor Yolanda Branche to investigate the Trust after D.C. Attorney General Irvin B. Nathan first leveled the graft allegations. Branche said earlier this month that her audit has been delayed by the federal probe. It is unclear which other agencies, if any, might be investigating.

“I am not at liberty to divulge any further information at this time,” Brown wrote. “I look forward to your cooperation with this matter.”

The letter: